Godzfirefly:
1) From a practical standpoint, too many options slow down the game as the DM has to consider them all before deciding on them (not as much of an issue for PbP, admittedly, but still a concern.)
Just because the monster has additional powers doesn't mean I'm going to use them. If I went to the trouble of adding a class template, I'm probably most interested in using those powers.
Godzfirefly:
2) The more powers you have, the more likely you'll include one that breaks an encounter. This is particularly an issue for inexperienced DMs that want to have 'super-cool awesome monsters!'
If that were to happen, I could just stop using that power, and resort to using the monster as written (and as bulked up into an elite). Instead of the extra powers being problematic, they're a nice fallback.
Anyway, broken powers can happen even with premade monsters, so I already have an approach for working around that.
Godzfirefly:
3) If you have too many powers (especially passive ones,) the monsters start stacking effects like PCs do. Which is another risk of breaking an encounter. (Again, monsters shouldn't really be acting like PCs.) This is especially an issue since there's a temptation to give every monster an option to use every type of action...Interrupt, Opportunity, Minor, Move, etc. At higher level, that's fine. At lower levels, that's a balance issue.
What makes you think I have that tendency? It sounds like you're arguing against them as a general thing, and no general thing works for everyone. I'm just thinking of them for myself.
Godzfirefly:
There is a bit of an issue with the desire that many inexperienced (or even experienced) DMs fall into to munchkin or power-game encounters.
That's not a concern for me.
Godzfirefly:
And, that can result in super-long combats. (Or super fast TPKs...)
As normal monsters can do the same, I already have ways to work around this.
If this were about creating monsters for other people to use, I'd tend to agree with you. But this is just for me. If my templated monster happens to have more powers than it can possibly use, I'm not going to find that confusing or frustrating, because I'm not expecting to be able to use all of those powers (though I still think, as a general thing, that a monster with a lot of powers just needs a few soldiers to run interference and buy time.)
Godzfirefly:
As for power points on monsters...what is the point of that?
The same point as for PCs. But did you read where I conceded that they're probably not needed for monsters to achieve the same effect?
Godzfirefly:
Monsters don't have to save resources for multiple encounters like PCs do, so they don't need power points any more than they need a difference between Daily and Encounter powers.
Power points aren't saved from encounter to encounter. They come back after a short rest.
jacktannery:
4) If monsters have powers to cover every eventuality, it detracts from the tactical-combat-mini-game which is a key part of 4E from a player perspective. What's the point of immobilising the brutes if they have a ranged attack?
"Brutes" would probably be, at most, two per encounter, since a PC template brute is an elite. I suppose I could have a group with a lot of elite members who show up frequently, but I don't see anything wrong with shaking up the "tactical-combat-mini-game" a little with a brute who is also artillery (especially since I'm probably focused on using the artillery powers I picked out.)
LonePaladin:
5) When a monster has the ability to inflict a condition on a PC, consider carefully the duration. If it's something that can effectively lock down that character -- like dazing or stunning -- give it a fixed duration, like until the monster's next turn. "Save ends" should be reserved for conditions that hinder or inconvenience, so that players can still do something. Under no circumstances should you have an ability that stuns with "Save ends)".
Reasonable general advice, and probably good for players too. Bear in mind that I'm not really talking about inventing powers here, so everything is going to have a duration.