From what I've seen in most designs for Electric cars they are very small to medium size cars. Is there any reason why electric cars cant be bigger such as a minivan? If you have any insight or know any big electric automobiles please let me know.
There is a perception that electric drive is best suited to city driving, where the constant start-stop traffic allows electric cars to express their full advantage through the use of regenerative braking. Electric cars have the greatest efficiency gains over conventional cars in city traffic and people tend to think that small cars are best in the city.
Another perspective is that electric drivetrains enable you to make a vehicle more compact.
However, i completely agree with you that minivans are a great opportunity. They usually would not need a long range if used for school runs etc. (and they don't need 760hp like a Model X - what am i saying?!)
Another reason that the focus has been on small electric cars is that the inverter/motor control electronics for higher power drivetrains is still developing. Heavy trucks are a perfect candidate for electric drive (imagine regenerative braking recharging your batteries while your 40T truck rolls smoothly down a steep hill), but the power required is enormous. I think Tesla are working on this.
Electric motors have been long time used in the industrial world, from low to high power. Indeed there are not so many who use big power. However, that does not mean that electric motors cannot be used for large capacity passenger transportation or even a truck. I think there are already many manufacturers offering electric buses, for example BYD electric buses.