While waiting, I'll put out some general thoughts here.
The idea that the pianist said the first composition did not have structure, that is extremely questionable. When I started the harmony part of music theory at beginner stages, there was a very basic structure: a "question" phrase above the I IV and V(7) chords, ending on V for a cadence that hangs in the air; followed by an "answer" phrase which might be the same thing but landing on the Tonic with a V-I cadence. Usually 4 + 4 = 8 measures. That is precisely what we have in the first composition. It's a textbook structure, and thus a structure. It happens three times: the third, an octave higher.
The second composition accidentally channels the Bach-Gounod Ave Maria in the melody up to the point where the original I think modulates and then it sort of meanders prettily into the weeds. We have the basic I IV V chords. There's a reason this structure got invented: it can't help but sound good and harmonious. There is also how it is played.
The issue of teacher feedback vs. a lot of people vs. some. The teacher part is tricky business.
A teacher - who knows how to do so (first prerequisite) - to teach composition also has to teach specific things, and that can get complicated. A student has to be ready to do the nitty gritties and over the long haul, and many teachers feel that they'll "lose" the student who will feel daunted by those nitty gritties. On the other hand, if they can encourage the student by way of their own explorations, those students might start discovering things, and that might be a good first stage. There is also the possibility that a given teacher may not know how to teach composition, how to structure that kind of teaching.
Meanwhile, I've played things when I started music seriously in the beginning, where my then-teacher probably heard potential in the raw, and encouraged it; friends without that much of an ear were taken by the emotion of it all or something, as I was --- Years later listening to those recordings, there's a bunch of things that bother me or that sound incomplete. I have much more the ears of a trained musician than I did. That might explain the disparate responses.