let me begin by saying that Skyrim is a good game, and that it is nice to see that you improved upon so many things in comparison to Oblivion.
I'm a gamer for over 20 years now, and even if some or most of the developers haven't played TES:Arena oder Daggerfall, i have

I'd like to say a few things about the game. Mostly parts i would say you made a bad choice changing/reducing them.
At first the spellmaker.
That the spellmaker ist missing is a big faux pas. This was one of my biggest sources of fun in the TES series.
In addition, i think shrinking the number of effects and reducing the magic system as a whole was also a mistake.
I know you are trying to enlarge your target group by making the game more accessable, but i'm convinced, that this can be done without cutting out the meat of a good fantasy openworlder.
The reduction of the attribut system down to 3 things, health, stamina and magicka also reduces the complexity and in fact the replayability of the game. You tried to compensate with the perk system, but that works only partially.
In addition shrinking the attributes and the magic system also results in less interesting loot, because there are so few effects, you can easiely encounter them within 50 hours of play.
And that quite frankly is not enough. I played Oblivion for over 400 hours. Skyrim gets boring after half of that at most. And that's sad because from a world standpoint, Skyrim is the more immersive experience.
Another thing that is very obvious later in the game, is the reduction of good quests. A lot of quests are 0815-stuff like bring me that, kill these etc.
That gets boring very quickly.
I was especially disappointed regarding the guildquests.
Most of the guilds quest are repetive, not very imaginative and very short. You can finish the mages guild series of quests in one or two hours. That is simply not enough.
I miss quests like the one from Oblivion where the painter has been imprisoned in his own picture or the detective quest in the first castle.
In Skyrim there are only a handfull of quests which are really interesting, and most of the are deadra quest which were of comparable quality in Oblivion.
The rest is mundane and boring kill and bring-stuff.
Don't misunderstand me. I like Skyrim, i had a good time, but at the end of the day i was saddened because it could have been so much better.
In the next game, i would be very grateful, if you would restore the magic system to its full glory, bring back the spellmaker, bring back at least a few attributes and spend a little more time on imaginative quests, so that even the older TES-fans like me, who played every TES-RPG to date can enjoy the full experience.
I also would like to say what i think are improvements in comparison to Oblivion.
+ The world seems more alive because there are more NPCs in the cities AND in the wilderness.
+ The gameplay expansions regarding smithing, cooking, marriage and buying multiple houses are fine, but i would have wished for more impact on the world. Marriage in fact has little effect, and in Oblivion buying a house was more interesting because of the curse.
+ The bards in the taverns are a nice addition, and the songs are nice too. Shorten the pauses between song lines(really annoying) and make the songs longer, then its perfect.
+ From a technical standpoint i have to salute you. Oblivion was a technical nightmare. Bad performance and a lot of bugs. Skyrim is so much better in this respect. A toast on you sirs!
+ The music is very good.
+ The dungeon design is a blast. It feels handmade and the shortcut at the end of the dungeon to the exit ist an incredible idea. Please give the inventor a bonus for xmas!

So..at the end i hope this summary is helpful as constructive criticism for the next game and shows, that i actually LIKE lot of the changes you made.
But it is clear to me, that you sacrificed to much complexity which resulted in less replayability, a less interesting magic system and loot. If that would change in the next TES-installment, it can be a better game.
Nevertheless i had fun with Skyrim, but i hope you will have a little bit more courage and faith, that the gamers will still buy your games even with higher complexity.
Don't forget, Oblivion was also a bestseller, despite the greater complexity and the bugs.
Thanks for reading.
I wish you all a merry christmas, and a happy new year.
Brakiri