I will cut this part out first:
It was intended to be a bit of hyperbole. If you want to call that "dishonest" you can.
My point is simply this: If you need terrain to defend your group, you're relying on that terrain being around, or having enough time to (say) dig trenches. Yes, there are rocks & boulders & trees & ravines outside. All of these can be avoided far more easily than, say, a 5'-wide dungeon corridor. Chokepoints are not everywhere.
(And I'll head down to here...)
I am not blaming it on bad design. Boring design, sure. But not bad design. I still run and enjoy 1e; I don't find that to be bad design, either.
All of the stuff you mentioned above, with the various ways in which the fighter did cool stuff? Could other characters have done the same? And if so, what's the point of the Fighter?
Let's go down a different thought experiment. I have a new spellcaster - call him a Caster for sake of argument. The Caster has a spell he can cast over and over again. What can the spell do? Well, he can make attack rolls and deal damage with it. Want to do anything else with it? Talk to your DM. Use the environment to your advantage. Improvise.
Is such a system sufficient for a spellcasting system? Is it an interesting system? Would you pay a game designer for it? (If so, I'll send my paypal address!)
-O