I don't think splitting it up like that is such a good idea; now, instead of searching through one file, I have to remember that there are several and look through them all, just for one conceptual protocol. (TCP has a similar issue, although most of it is still in 793.)
As for the extra verbosity, I'm not sure what to think; while some things may be specified more precisely, standards should also attempt to be concise and to-the-point. Some of the sentences in the new RFCs seem almost parenthetical (e.g. look at the description of GET.)
OTOH, that means I don't have to dive through the minutiae of response message format when I'm just looking for the basic header stuff. All the important concerns (core, caching, conditional requests, auth and forwarding) get their own RFC and are thus easier to skim and search through. Although 308 and Range (and Prefer) also getting their RFCs is a bit weird. Likewise, syntax and routing get RFC 3270 so if you're implementing a client or server the reading experience should be much tighter,
As for the extra verbosity, I'm not sure what to think; while some things may be specified more precisely, standards should also attempt to be concise and to-the-point. Some of the sentences in the new RFCs seem almost parenthetical (e.g. look at the description of GET.)