Overall I agree... there's definitely demand for more terrain, and these are the best spots for it south of the Sierra Nevada.
2) There isn't nearly enough beginner terrain. Summit Run is nuts. I have no idea what level of terrain is sitting there in the proposed expansion, but hopefully they figure out a way to get the beginners spread out better.
3) These ski areas get awfully busy and while adding terrain helps spread people out, the other thing they need to upgrade is the parking/shuttle situation. If you add more skiers/riders with more terrain you need to add parking too.
4) Is there a lift B that I'm not seeing or are they just avoiding the letter B because it's confusing due to the BB name?
To the extent possible, it would be great for Alterra to point beginners toward Snow Summit. But plenty will continue coming to Big Bear, so giving them more space is, as you say, a great idea. I haven't looked at this enough to know whether they're actually planning on increasing parking/crowds, or just better-spreading-out the current crowds. But SoCal potentially a bottomless pit of demand, and adding in more parking is just going to add more stress to the access roads and the city streets.
Lift B is still in the master development plan (
https://www.fs.usda.gov/project/?project=63391), replacing lifts 2 & 5 at Bear. But it sounds like Alterra's current planning hasn't identified it as a near-term priority, so they haven't applied for it yet.