I don't think degradation arises from splitting infinitives or starting sentences with coordinating conjunctions. But I do think it's a shame to not fight back against the phenomenon of the persistent ignorant misuse of words allowing that misuse to become enshrined as standard English. I think that there is a distinction worth preserving between "disinterested" and "uninterested," though it always came down to usage in the end, not a lost rule, because there never was a rule (as with those confounded split infinitives). Once, when compiling the reports for my class, I sent one back to the PE teacher who had written "Paula has not done as well as expected because she is disinterested in athletics." He hadn't broken a rule but (to my mind ignorantly) had selected by far the less appropriate of the two words. I was overruled.

Another misuse that is now acceptable is "begging the question" for "raising the question." It now hardly ever possesses its original meaning, but hey ho. A little piece of me wants to smirk at this example of pompous misuse, but, well, if that's how people want to use the expression...

But don't get me started on "albeit" or "prior to," both crimes against our beautiful language, punishable by loudly-expressed derision. I'm not having "alright" either, not ever! Although I already realise that I may not be altogether rational in rejecting it almost out of hand...