I think Tesla's strategy is to start with the total battery supply and allocate batteries to vehicles with sufficiently high margin that they can scale as quickly as possible.
They delayed refreshing the X and S for a long time, I believe, in part because these two models are low-volume and therefore don't warrant a high allocation of battery supply and manufacturing floor space. Why refresh them now, then? I think they are using the 2021 refresh of X and S as a spur for the 4680 battery ramp (see conjecture that Plaid+ is going to be 4680).
Adding more models and variations doesn't do them much good when their demand for the mainstream 3 and Y far outstrips their battery supply, both today and into the near future, even with them ramping battery supply as hard as possible.
Brands that are making a wide range of electric vehicles are taking a significantly different approach. But seeing as they too will be constrained by a small supply of batteries, I am not sure the diversity will be as valuable on their bottom line.
That makes total sense! I'm just surprised they didn't focus on commercial market after 3, especially commercial spaces, range is usually not an issue. Work trucks and vans don't need a lot of ranges.