As I recall, oblivion and morrowind did this in some instances, but rather than warn you that you are too weak to do the quest they didn't even give it to you. Caius Cosadas and daedric shrines for example.

I always train my character a few levels before doing the main quest in any game I'm playing to avoid being too weak to survive.

Players new to the elderscrolls should take their time to learn how the game works. Those who are in a hurry to "beat the game" deserve to get beat down a couple of times.

If I find an area too hard for my character, I usually go some where else until I am strong enough to get past the hurdle. I don't blame the game for allowing me to bite off more than I can chew, I rather expect there to be areas that I won't be able to waltz through unopposed. If it happens to be in the main story of the game even better, the damned things are too short anyway.

Exactly. I also hated the level restrictions on Daedric quests in Oblivion, it just breaks immersion and makes my open world game feel far less open world.

No. I like to be beaten to a pulp. Then when I come back later and faceroll them it is a good feeling.

Let's not make the game hold your hand too much. Some think that is what Oblivion did wrong.