Depends on hat you consider "function". All Tesla vehicles are very aerodynamic. That means of course a bit less "practical" body shapes. Like lower headroom towards the back. So the question is, do you define functional as the most easy to use design, or the most efficient design? Efficiency does mean higher range, which is important for electrical vehicles.
Has nothing to do with the body shape. 2 simple examples:
1. I don't think I've heard anyone (who doesn't work at Tesla) ever say anything positive about the driving yoke.
2. Using touch screens for everything. Obviously touchscreens have the benefit of allowing the UI to be reconfigurable, but other companies have done a much better job of having important physical buttons/controls where it makes sense.
I've driven a friends Plaid with a yoke, I was surprised that it felt more like a yoke on top of regular steering column rather than a yoke from a kart or something that had progressive steering. Having to do hand over hand in order to turn tightly was very odd to use.
I haven't read many people who actually have a car with the yolk have anything negative to say about it. Most of the comments I've seen are "yeah it was weird to get used to, now I like it" with a couple "I returned the car".
Agreed it could use a few physical buttons (but not many, voice control + the steering wheel controls are the majority of my usage). They also really need a new lead UI designer.
In the context of the discussion, I considered "function" to be referring to the body shape. The points you name are a different discussion. But most Teslas don't have a yoke. That is so far limited to the Model S.
I watched the yoke thing pretty closely. The positives that I've heard all center around the turn signals. Apparently a lot of people get used to them and actually like the touch buttons! A surprising number prefer them! TBH, this kind of shocked me, but watching them use it makes it make sense.
The horn button gets universally negative reviews. The yoke shape itself is more mixed, but I don't think I've run into anyone who'd prefer it over a round one. It more mixed between "I hate it" and "its ok". :)
