I assume "Dwemer" in this case refers to creatures related to Dwemer, like Dwemer Centurions or Dwemer ghosts, not actual living Dwemer. That being said, while the Dwemer were quite interesting, Morrowind and Redguard already had a lot about them, and it would be nice to see other civilizations expanded upon.
As to dragons, they exist in the Elder Scrolls world, that's why there's a statue of one in Ebonheart (although whether it's supposed to be a generic dragon or if it represents Akatosh I don't know.) but they wouldn't be something you'd be fighting as leveled monsters.
I think that normal creatures (like bears, wolfs etc) should be the majority of creatures you encounter. mythic creatures like trolls, skeletons and such should take some effort to find, they are mythical after all so it's not like you see them every day.
We say them as "mythical" because in our world they only exist in myths, but in the Elder Scrolls world, things that are the stuff of legends and fantasies are quite common place. In a world where there's elves and orcs running around all over the place, a guild dedicated to the practice of magic, and all that, it almost seems unrealistic for mythical and fantasy creatures to NOT be commonplace.
Besides, how do you even define "normal" when talking about creatures in a fantasy world? In Morrowind, nix-hounds and alits might have looked pretty strange to players, but they're pretty normal in the setting of Morrowind, they're really like the game's equivalent of wolves and bears, only better since you won't see them in real life.
Skyrim is totally baded upon the ancient Norse culture, it does have trolls.... The Udyfrykte is a unique creature..... And the Norse also had goblins...
Although any kind of logic should dictate that there are other creatures like the Udyfrykte (and in Oblivion, there even WAS an Udyfrykte matron, but she looked the same as a troll.), after all, a completely unique creature with no others of its species doesn't just pop out of a rock, but you're right, the Udyfrykte seems to refer to a specific unique creature, not an entire species of creature, and I'd guess that the reason Bethesda made Rieklings is because goblins were already done in Tribunal, so they wanted something else in Solstheim, in the end, goblins and trolls seem pretty fitting for Skyrim,
No, they debuted in Daggerfall. People make Morrowind up to more than it deserves...
Well, I played Daggerfall, but I didn't recall if I ever met them in it, that's why I said they appeared in Morrowind, I hadn't meant to imply it was their first appearance as I wasn't certain.
If the province is going to be dull (snow, alps, etc.) that doesnt mean you gotta make monsters matching that, I'd really enjoy a larger variety mosnters rather than ones fitting to some province.
Variety is something I definately want, but if Bethesda wants variety so much that believability is sacrificed for it and you get creatures that don't even fit their surroundings at all, you just get people asking "What the hell?" Bethesda should do lots of variety, but keep it limited to what fits the setting. Since this means that if the setting itself is dull, the creature selection would likely be too, Bethesda must, of course, also not make the setting boring. Netches and nix-hounds were pretty strange, but they didn't seem out of place in Morrowind because Vvardenfell itself was pretty different from what you would typically see in fantasy, so while they may have seemed fitting there, they might have looked rather strange if we saw them in the Great Forest as modeled in Oblivion.