I'm very picky when it comes to poetry. There is always justification -- I'll even present some -- but in my opinion ending a line with a or the is the sign of a bigger problem with the poem itself.
When I saw this topic I knew that I had actually done this in a misguided attempt to write a poem in trochaic meter:
Nothing is as I imagined.
We are blatant almost-gods; we're
angels! serving other angels!
glorifying God! It's raining ...
Let it rain the hardest rain, and
may there be no sun or anyone.
Trochaic meter in English verse is not to my liking and attempting to compose this poem in trochaic meter accomplished absolutely nothing. There is no reason the poem could not have been broken up into iambic tetrameters. (Maybe I'll revise it!) In fact, I don't see much point to trochaic meter at all, but this comes back to the picky-when-it-comes-to-poetry part and very possibly to my lack of experience.
It's a linguistic fact that English is an iambic language. Whether in metrical verse, good free verse, or prose, language patterns are naturally iambic. In my opinion, any attempt to employ different metrics must serve a very good purpose and be done well enough to satisfy that purpose. I won't win a popularity contest with what I'm about to say next, but this is why I have very little interest in haiku. English is accentual. Unlike in Japanese, in English one cannot hear syllables in some useful, meaningful way. It seems that to fully appreciate haiku in English, one has to focus on haiku's other inherent characteristics. This isn't in itself a bad thing, but in my opinion it's a severe limitation. It deprives a poem of a major device: the rhythm (or other noticeable pattern) of the language. Additionally, because haiku is such a short form, people will try to pack more into the three lines with their syllable count by omitting articles altogether! This results in a completely unnatural experience as far as I'm concerned. While I understand why pidgins have developed, "no can do" simply does not work for me in any poem. Here is a haiku by Meisetsu:
With a lantern,
Someone walking in the night,
Through the plum trees.
This translation by R.H. Blyth is about as close to haiku as one can get in English, and it doesn't omit articles. Therefore, it appeals to my purist sense insofar as the use of articles in English goes and because it's otherwise unmistakably haiku. Nevertheless, though lovely, as an English speaking American, I am not inspired at this time to make extensive use of this Asian form.
Longfellow composed "The Song of Hiawatha" in trochaic tetrameter to mimic Native American language and for other culturally relevant reasons. The linked article points out that this is the same meter used in the Finnish epic poem Kalevala. Finnish is very close to my own first language, Estonian, thus the meter is also the same meter used in the Estonian epic poem Kalevipoeg. But, "Trochee is a rhythm natural to the Finnish language—inasmuch as all Finnish words are normally accented on the first syllable—to the same extent that iamb is natural to English. Longfellow’s use of trochaic tetrameter for his poem has an artificiality that the Kalevala does not have in its own language."
With the exception of words borrowed/adopted from other languages, all Estonian words are stressed on the first syllable. The language is trochaic, and trochaic meter is natural. Even so, many of the finest Estonian sonnets are written following the rules I use to compose iambic pentameters in English. Lines in Estonian work even when broken up into iambics. This is because there is an abundance of one syllable words and multi syllable words that don't impose trochaic limitations the way a two syllable word would when used at the end of a line. Yes, a and the are also one syllable words, but though they are often promoted (stressed a little) in iambic pentameters (for example if the result would otherwise be three unstressed syllables in a row), it is not natural to give undue stress to these articles in English.
This has not been a digression. It goes directly to why I think ending a line with a or the makes little sense in a poem. It doesn't work with the English language's natural iambic pattern. This is true even for free verse. If I could only choose one poem to be my favorite poem, it would be James Wright's "Twilights." It is composed as free verse, but there are no nonsensical line breaks or enjambments that disrupt the natural flow of the English language present even in this free verse poem. I get that not all poetry has to have rhythm. I can appreciate other features like the way a poem looks typeset on a page. But while I like some poetry that has no rhythm, I do tend to favor musical poetry, poetry that also makes use of the natural patterns of the language it's composed in. If someone were to read me a haiku in Japanese, I would be able to tell that it's a poem, a haiku. I don't have to know the language to hear its music. In Japanese, that would be the syllable counts of the lines. In English, it would be the accents, the iambic patterns in the lines. Why strip that substantial component from poetry by writing haiku in English or by using articles haphazardly at line breaks in English verse? And for me, that's the sign of the bigger underlying problem in verse that uses lines ending in a or the. It's only my current opinion. English is my primary language, and I like rhythmical/musical poetry. I've also admitted that I like, and for other reasons can appreciate, some non-musical poetry (e.g. concrete poetry that looks good on a page, some free verse, even some haiku). But I don't like cacophony, and that would be poetry that outright rejects a language's main feature (in the case of English its natural rhythm) with lines that end in a or the.