Assassin’s Creed 1 has revolutionized the seventh generation of consoles
with the ability to climb every handhold in an open-world.
That said, most surfaces are not full of handholds, which means
you can’t climb absolutely everything.
This leads to interesting choices.
If you need to infiltrate a fortress - you can’t just choose any wall to climb,
but have to search for an applicable route to get to the top.
This applies to all environments - while running around city rooftops
you often need to plan a little bit ahead.
If you need to run away from guards, climbing the first wall you see might
not be the best solution.
And even just climbing viewpoints requires more actions than
just pressing up.
All this makes you more involved with the process of parkour.
Of course, this doesn’t mean that being able to climb absolutely
everything is worse, - that’s just two different approaches.
But the first Assassin’s Creed does show some advantages of
not being able to climb absolutely every surface you see.