mprogs -can- be spammy if they're verbose and frequently do their thing. Such as a spammy greeting, or a yell every 7 seconds.
Not that you can program how often(in time) they go off, only the odds of how often it'll go off. <-- this only applies to yells/says/area wide mprogs
I think they can be fun, when used right, and add something to an area. I'm not sure what talkscripts are capable of, so I'll reserve my judgement, but they can be added to areas to create a little "side-quest" sort of thing, too.
Problem is, rewards are renewable, and you can just farm them everytime the game shuts down if they give good rewards(*coughthatcrystallinecough*). I don't do this on principle, but it is doable.