There are Buddhists and then there are Buddhists. I call myself one, Steve Jobs called himself one, but there are also a lot of Buddhists who live more dogmatically. I have a feeling you will find those more in Oriental countries than among the self-converted types. Personally I think Buddhism embodies the perennial philosophy best which is one of the reasons I agree with much of it.
Hardcore Buddhists (sounds like a paradox but alright then) could be expected to say that they appreciate the way psychedelics lead them to but they want to go use meditation and other practices that go at a normal pace and don't collapse for the most part like a house of cards when the effects fade. Of course we retain memory of the state but that is not the same as sustaining it.
It's certainly possible such Buddhists would say: meditation is better, and I agree myself that it is superior while being similar in many ways if you delve deeper. The dissonance that makes me not do it more often is the unrest many things have given me ever since I lost my meditative tendencies. The unrest makes it hard to do it more often even though it has the power to remedy part of it! I appreciate psychedelics to make me remember and realize every once in a while so that I can reconnect and get a chance again to get back into it. I have been trying for the past while, but still don't meditate nearly often enough as would be effective for my purposes.
But a significant issue Buddhists might have especially the ones who are not masters, is that psychedelics have a fair potential to produce a state of makyo:
http://en.wikipedia.org/wiki/Makyo
I have experienced Makyo sober during a week retreat of Zen meditation (sesshin), described it to others there are they explained the concept to me further. You should not read too much into the word 'devil' in the wiki link, while it does involve delusional experience from readjusting sensory stimuli or from some intricate mechanism, it is considered a natural part of the process and as such not really negative.
I think that the non-sustainable aspect of psychedelic states and the makyo-like aspect arising also from the process not going at your own natural pace are reason enough not to attach too much value to psychedelics.
On the other hand I'm sure many moderated Buddhists whom you might call reformed Western Buddhists (?) welcome psychedelics as a tool or facilitator. I guess I do too, I value psychedelics a whole lot. But in the context of Buddhism I do really have my doubts and think the emphasis should like on sustainability.
FYI: A method that I feel is great for producing less of a makyo effect with acid is instead of taking a large dose in one go, start with a moderate dose and almost at the end of the plateau drop a double dose to account for tolerance and deepen the state that is at that point much less muddled but instead clear and crystallized because you have passed the peak.