Needs More Templates: Not really. Most of the templates were more trouble than was necessary. What is the difference between an orc or human skeleton? An elf vampire or a tiefling vampire? Most of these changes would only need to add a few key racial traits and description to the monsters. Similarly, swapping out lich spells or giving a vampire casting is much easier than having to build a full NPC and then rebuild him with the template. A few others are redundant (half-fiendish compared to cambions or tieflings) or unneeded (summoning aside do you need the celestial template?)
Needs Standard Humans/Elves/Dwarves as Enemies: Didja MISS the giant section of NPC stat blocks? Cultist, Arcmage, Knight, Thug, Guard, etc? THERE are your Human NPCs. Want elves and dwarves? the DMG has a quick page of add ons to make elven archmages, dwarven knights, etc. The DMG page also has some simple monster race stats too, so you can make hobgoblin cultists, skeleton knights, orc thugs, etc. You can even use this page to customize other monsters (elf vampires, hobgoblin ghouls) if you want.
No, I saw them. I just think it's a tad ridiculous that I have to edit a monster to get a basic elven scout, or a dwarven warrior or something like that.
For example: I was personally disappointed that atropals weren't in the MM, because they're a personal favorite monster of mine. But you'll notice I didn't include that in my list of gripes earlier, because I don't think it's a legitimate complaint. Sure atropals are cool to me personally, but they also are kind of a niche monster, and the MM was pretty packed as it was, so I can understand why they wouldn't be included.
It would be an unusual campaign, though, where the party didn't encounter elves, dwarves, skeletons or zombies even once. So the fact that they don't get any (or, in the case of basic undead, more) attention seems unusual to me. Not quite a mistake, not quite an oversight, but a design/editing decision I don't personally agree with at all. So a gripe, I guess. I hear a lot of people say, "Oh, there's no difference between an orc skeleton or a human skeleton." Agreed! There is, however, a very large difference between a human skeleton and an owlbear skeleton. Or an orc zombie and chimera zombie. This is why a template would've been useful, and it's baffling to me that's lacking in a book that managed to find space for flumphs, xorn, and like six dang pages for modrons. Did the designers really think, "Oh, we don't need to include stats for a dwarven warrior. When do PCs ever run into those? But let's make sure to include the merrow, everybody knows mutated evil mermaids are a mandatory part of any campaign."
So not only did it fail to cover the basics (in my eyes; yes I can modify the NPCs but it strikes me as odd that I have to modify anything to make a bog-standard elf), what is there is overly-focused on "evil humanoids what hit you with clubs." Seriously. Like a dozen monsters fall into that category. Goblins, hobgoblins, bugbears, gnolls, orcs, ogres, trolls, ettins, hill giants, grimlocks, troglodytes, kobolds... and I'm probably missing a few. We have pages and pages of those. And even where there were opportunities to differentiate some creatures mechanically (like salamanders), nope. We got more of the same; evil humanoid with oh yeah sure fire resistance.
Again, I love the 5e MM. I'm just saying it wasn't perfect.
