Your assessment that ENTERPRISE made Vulcans too emotional is one which I happen to share. My feeling is that to get some of the good talent that they got to go through the hassle of wearing this nappy wig, of having rubber glued to their ears and all this, they were going to have be cut some slack. As in allowing these people to emote. It goes without saying that actors rely heavily on their facial expressions, body language and emotional range to realize live-action characters, almost all of the time. In a way I can understand, but ... I would rather have bad actors acting all unemotional and stoic as Vulcans, than have big names in the makeup playing as themselves. But that's just me ...
I don't want to imply that all Vulcans on the show were excessively emotional. Gary Graham, Thomas Kopache, Gregory Itzin, and Kara Zediker were all good at playing traditional Vulcans. Jolene Blalock was good at it too, for the most part, though they were clearly interested in making her more emotional for much of the series.
It's interesting that you bring up the shows guest actors being subjected to heavy make-up, since most of them had played such roles on previous Trek series.