This "I can't roleplay without attributes" is still elude me. Why do you need a number to remind you about some characteristics of your character?
It could hinder even hinder it, for example because intelligence is mainly a magic attribute, playing an intelligent non-magic warrior wasn't really a good idea. To help your RP you could add a little bit of intelligence to your character after every level up, but you would lose some valuable points you could've spent on more important things for a warrior like strength or endurance. And why would you raise the intelligence anyway? The game doesn't care about your RP, points spent on intelligence will be wasted if you won't use magic, or any related skills, which in a Warrior's case is quite possible.
Ahhh please don't confuse attributes as system and flawed implementation of attributes what was done by devs, if they cant implement attributes in better way thats not problem of Attribute system, thats problem of implementation.
I mentioned some threads ago mod Intelligence overhaul what expand features of intelligence furtherer then just increase of Magicka.
So without attributes why shouldn't Skyrim be called an RPG? What attributes do anyway? They make the characters different from each other. The same thing can be done with skills and perks. You could say that there won't be as many combinations as there would be with attributes, but I don't think that's true. Oblivion had attributes, different characters will still feel similar just with different attributes.
So if Skyrim's an "action-adventure game" then I think all TES games were "action-adventure games" ever since Arena.
First person, action role-playing, sandbox actually, and yes Oblivion has most bad implementation of attributes in series.
And on the OP's point: what's the difference between achieving 100 strength and achieving 100 weapon skill and getting all the perks in it?
Difference?
Oh well don't try disassemble blocks of RPG by parts and try put them against each other, attributes skills and perks work in synergy if implemented well, its the same if some one take spinal cord and brain from organism and then say thats brain not needed at all, because spinal cord control movement also.
Attributes are natural abilities you born with them and then they grown, your skills and perks is acquired abilities you learn them, remove attributes and you remove your natural side, its that same if races was axed.