...about the initial chapters in the main rule book.
I do feel that they don't offer a hugely varied character base, which was greatly improved in RoB.
But for the largest richest chapters which are still limited to the codex regulations of ground troops to be the same size as other chapters. Take the Ultramarines for example, they have an entire empire bankrolling them. And a huge pool of manpower to draw from if they need to. There's only so much vehicle crew and support marines that it's worth having.
Instead of being jsut a bit more discrimanting about their recruits, why not send entire companies worth of troops to be seconded to the deathwatch. Let them get some experience and you can have them trickly back in if you need the man power, like they would have done after Hive Fleet Kraken.
So maybe most of the DW you'll see are Ultramarine or Blood Angels or even Imperial Fists.
- with all of the other Ultramarine love that exists I just took the line to be accurate