Look, no offenses, but that's terrible and shallow criticism:
> You can't be the successor of a country,
The we to whom it is addressed constitute a country, and can certainly be collectively successors to the past state of that country
> you even more can't be the successor of the present instant happening right now
But the time it referenced began in the (close, but still) past from the time it was recited, and the emphasis on that as already a past that we are already successors to when we contemplate it fits quite well with the theme of continuous progress of the poem.
> It's content-free, like a bad political speech. "We are striving to forge our union with purpose." As opposed to striving to forge it accidentally?
No, striving for common direction instead of perfection (though putting it that way in a poem would be inexcusable); you need to stop reading sentences alone out of context: “...that doesn’t mean we are striving to form a union that is perfect. We are striving to forge our union with purpose.”
> It's clichéd: "We close the divide because we know to put our future first, we must first put our differences aside.... while we have our eyes on the future, history has its eyes on us."
That’s a fairly specific reference, not cliché.
> It uses rhyme for cheap effect: "We seek harm to none and harmony for all."
That's...not using rhyme for cheap effect.
> It is a shame, when there are black poets like Derek Walcott out there
Kind of an odd alternative to hold out to a US inaugural poet, as Walcott is, while certainly Black (as now an absolute majority of such poets have been) both not-American and dead.
> I expected something as bad as Maya Angelou
Pretty much all the negative criticism of “On the Pulse of Morning" is of it as a decontextualized text, rather than in its actual role. And it take someone taking the same approach to Gorman’s work and blindly expecting everyone else to do the same to even begin to think the sentence the phrase “as bad as Maya Angelou” is something that could even sensibly be used, non-ironically, in this context.
> brutally reviewed by Paul Beatty
That isn't a review, of a throw away statement of distaste for a work. Which isn't the same thing.
> People get exposed to this kind of "uplifting" stuff and will think that's all there is.
While it is certainly not a requirement for poetry to be either targeted at a broad audience or uplifting, any art has a context and intended audience, and inaugural poetry is a pretty specialized niche where both breadth of appeal and uplifting character are, usually, things that makes sense. Having more depth than just that is, of courses, to be hoped for, but Gorman’s piece did.