Hinduism does have a problem that many of the hindus seem to think that "hindus are only born and one cannot convert into a hindu". I personally think this is suicidal for hinduism. Hinduism should get rid of caste discrimination (which I believe is already in process) and streamline a process by which non-hindus can convert into it (without the question of caste).
That aside, the main issue with muslims not leaving Islam has to do with death threats (for apostasy), and complete social isolation from muslims and non-muslims alike (as you mentioned above) if they leave Islam. I think, we all have to think towards a solution for all these challenges than just trying to prove that our current faith is superior.
