World Congress of Jewish Studies - Liturgy
The question Avi dealt with in this lecture was whether these compositions were meant to replace the standard text of the blessing, or to supplement it. This is a question that has been asked about other forms of Piyut - especially the monumental compositions we get a glimpse of in the High Holiday mahzor, the Yotserot and Kedushta'ot. Ezra Fleischer has claimed that they were indeed intended to stand on their own, as a sufficient form of prayer. The difficulty is in proving this.
Shmidman pointed out that many liturgical Genizah fragments were clearly copied in a way designed to skimp on space and outlay, leaving it to the reader to supply many different elements. Therefore, the absence of the standard blessings is not a sign that they were not meant to be said - perhaps the scribe assumed that his reader knew those blessings by heart.
However, there are some (13) pages which supply a complete text, and leave nothing to the imagination, or the memory. They spell out all the verses and all the blessings to be said, without abbreviation. But they do not provide the canonical text of the blessing. Therefore, it would seem clear that these copies reflect a practice that required the recital of some elements of the blessing - the "Baruch Ata" formulae, and certain verses that preceded them - but not others, which were replaced by the poem.
This is, though, an intermediate stage. Originally, it would seem, most of the verses were dispensed with as well, and the poetic compositions were recited in pristine independence. Later, however, the need was felt to add biblical verses - perhaps, to anchor the frighteningly original lines in a more familiar text. This later stage is reflected in the akwardness that these verses create, interrupting the flow of the poem into the traditional blessing.
I often feel that kind of akwardness on Rosh Hashana and Yom Kippur, when the hazan (and the congregation) tries to incorporate the unfamiliar structures of the piyutim into the regular forms of prayer. For instance, the difficulty with refrains. The piyutim were written to allow the congregation to respond to the leader with a shorter, repetitive exclamation. In the shuls I have davened in, people seem reluctant to make do with this short response, and squeeze in the entire line of the piyut. And so it becomes easier for everyone to just mumble the passage to themselves.