Yeah MM 3 was pretty heavy power creep/out of whack CRs.
How so? I picked it up and haven't really noticed anything jumping out as unbalanced. Admittedly, I haven't had chances to use the vast majority of the critters in a game session yet.
Yeah MM 3 was pretty heavy power creep/out of whack CRs.
Yep, the CRs in MM 4, MM 5, and the Eberron Core Rulebook all show significant power-creep relative to MM 1. We got a major shock the first time I used one of those monsters against a core-only bunch of PCs.
A big part of the issue is that the core of 3.5e was written on the assumption that PCs wouldn't be optimised, that they would mostly be single-class, and that they would find items using the DMG's random treasure tables, rather than buying them (or making them in any numbers). Obviously, those assumptions were very quickly shown to be faulty!
Another part of the problem was that big bits of 3e just aren't as robust as they seem. Basically, anything higher than about 10th level, anything to do with item creation (and, by extension, purchase), anything to do with monster-as-PC (or shapeshifting), and the multiclass system are all problematic. I get the impression that while the game as a whole was massively playtested, that effort was massively concentrated on some areas, with others only getting a minimum of attention.
Plus, there's Cthulhu.
To answer the original question: YES!
Let's try an experiment: Let's replace the word "monster" with some other words and see if a similar sentiment makes any sense.
We already have plenty enough monsters. Why would anyone want more than what's already out there?
We already have plenty enough non-player characters. Why would anyone want more than what's already out there?
We already have plenty enough spells. Why would anyone want more than what's already out there?
We already have plenty enough magic items. Why would anyone want more than what's already out there?
We already have plenty enough campaign settings. Why would anyone want more than what's already out there?
We already have plenty enough adventure modules. Why would anyone want more than what's already out there?
We already have plenty enough fantasy fiction. Why would anyone want more than what's already out there?
And considering that Paizo GIVES their material away for free in the PRD, I won't begrudge them a new bestiary every year. Game material in HTML $0, Electronic Art (PDF) $10, Fancy Hardcover $40.
Really?