Usually that's what thing that differentiates >=premium cars from the rest. If you buy a Skoda, you get packages. If you buy an Audi (same conglomerate), you can customize everything as you like.
For the same reason that car manufacturers offer different models for the same product (personal transportation): like the A, C, E, S class (in the case of Mercedes). These classes allow a producer to differentiate between consumers with different spending power. If you offer just one product at one price you can't capture the whole market (ie. you sell too little / too cheap to rich people and can't sell to poor people).
Apple recently started going this way as well with the introduction of the Apple watch. If you look at all the models and options they can cover a very broad price range. Differentiating between the watch sport, the watch and the watch edition. Add to this the different sizes (38MM and 42MM) and the different bands and you get a very nice price continuum between 349$ and 17000$.
Add in the fact that it's not millions of variations (really only a couple dozen now). Tim Cook famously said in some conference a while back that all of what Apple sells can be fit in on a table in front of him. I don't think that guiding vision has really changed.
Furthermore, it's not clear if the Apple watch will be successful. I wouldn't use it as a guideline for a successful product strategy - yet.
Why not go the Apple approach - provide a small number of models that satisfy a pareto-split percentage (80%+ including the more profitable markets) and leave the remaining percentage either to aftermarket partners or competitors?
That's the approach Tesla has taken, focusing primarily on the highest margin portion, and filtering down.
Tesla isn't planning to be a "big player in the automotive industry". They plan on creating new product market, which just so happens to be compatible with the existing infrastructure. The incompatibilities (i.e., no ICE/gas) is a feature.