Less forward lean for park and general all mountain.. more forward lean for steeps and racing. However, I suspect the real reason most mainstream boots have less aggressive forward lean is because that is more comfortable to stand in and walk around in.... therefore more people will like the feel of them trying them on in the shop who don't know that they'll want more forward lean for actually skiing in the boots.
I went to less aggressive boots when started skiing greens and easy blues with my young kids. Just too exhausting standing around in race boots not actually skiing hard... but for "skiing" they feel great.. Solution.. quiver of different types of boots, all with the same BSL..
There is no reason skiing steeps require more forward lean.
I ski steep couloirs regularly, 45 degrees and steeper, and I ski a Lange boot, about 12 degrees.
It works great, and it lets me pressure the front of the ski and get out of the back seat.
It's also a lot less effort on the quads.
Walking has nothing to do with it.
But it depends on your bike proportions.
Lemaster has a great test that tells you if you have the correct lean angle for you. Read that and you will see.