"Everything should be made as simple as possible, but not simpler." -- Albert Einstein.
But yes, Occam's Razor is not a natural law or anything like that. It's a heuristic -- something that usually points in the right direction but very much not guaranteed to be correct.
It's arguably a bit more than that, on account of Solomonoff induction. An "Occamian" prior that weights computable hypotheses according to the fraction of computer-program-space occupied by programs that compute their consequences provably performs -- in an admittedly somewhat artificial sense -- at least as well in the long run as any other prior, provided the observations you see really are generated by something computable.
More practically, there has to be a complexity penalty in the following sense: no matter what probabilities you assign, almost all very complex hypotheses have to be very improbable because otherwise your total probability has to be infinite.
In two posts, Bayesian stats guru Andrew Gelman argues against parsimony, though it seems to be favored 'round these parts, in particular Solomonoff Induction and BIC as imperfect formalizations of Occam's Razor.
Gelman says: