I always snicker whenever someone tells me this. At the APS Centenial March Meeting in Atlanta, I presented a result from my work which I stressed, was consistent with signatures of spin-charge separation in a 2D system strongly-correlated system. A prominent physicst in the field commented at the end that I was pushing the envelope too far and should wait until more evidence come in. We had the same comment for the paper that we submitted for publication.
.. and here, I get accused of discouraging progress in physics!! :)
The difference being that, unless you have completely thrown out the history of physics, LEGITIMATE challenges to existing ideas can only come from, not from personal preferences, but valid experimental observations. You do not make any progress in physics by citing personal TASTES in how the universe should behave. That's just plain arrogant. You can't dictate that a neutrino should not change flavor just because you have a problem with things transforming itself into different "genders". The ultimate arbiter of what is valid is still experimental verifications. So far, there has been NONE that would challenge the validity of QM.
I know I've said this before, but it appears that people seem to trivialize the fact that it works! I don't know whether these people are aware of the breath and range of area that QM has been applied to. If one considers this, it is astounding how well it works in such a diverse area of physics!
Having said that, I still would love to see indications that QM may be "generalized" by something else. However, it will be in the form of an experimental discovery that offer tantalizing hints that QM may fall short of describing such phenomenon. It certainly will NOT come out of someone's personal preference or discomfort of QM. Such things have never been used to justify publication of any physics papers in respected journals.