I love the collection of monster in new 4th Edition Monster Manual and I love the array of powers that the designers have given them. I know some people are lamenting the loss of certain creatures (centaurs, rust monsters, metallic dragons, etc.) but never having had an attachment to the D&D world of old I guess I’m just as happy with these things as without them.
There are several reasons for choosing the creatures they did, not least among them that they wanted to keep a few hold-outs for the Monster Manual 2. While some people will insist that this is a greedy move by the company I guess I personally would rather see a book have some “normal” monsters and some bizarre monsters rather than have the basic Monster Manual be all the boring stuff and then have the later MMs be full of ever more crazy creatures.
One problem I have with the Monster Manual is that there are very few options for introductory adventures. At about level five onward you have the option of sending lots of lower level creatures at a party (or perhaps “pumped up” versions of lower level creatures) but of course there are no lower level creatures for a starting party. It seems your basic options are either Kobolds or Goblins. I wanted to have another option so I created Gribbs.