The idea is not to just remove things for the sake of removing things, but to engage in a cost-benefit analysis. Most of the things listed above either are very widely used or don't cost much or have other downsides to maintain. By contrast, when things have been removed from the Web platform in the past, it was because they were causing problems out of proportion to the amount of breakage induced by removing them. In the case of XSLT, the problem is the attack surface that it adds.