Tesla is just being sensible here, given the dynamics of the car market.
Point 1 - the car market is shifting heavily to sell more SUVs. (For some reason) buyers are preferring them to traditional saloons. [1]
Point 2 - as a result, many car manufacturers have a range of SUVs, which absolutely cross over with --and cannibalise-- their saloon options. For example:
* Audi has the Q3, Q5, Q7, and Q8
* BMW has the X1, X2, X3, X4, X5, X6, and X7
* Mercedes has the GLA, GLC, GLE, GLE coupe, and GLS
All of these are SUVs, and all of them cross over with other (saloon) models from the manufacturer.
If Tesla wants to sell more Model 3-sized cars to consumers, it needs a small SUV alongside the Model 3. This is just good basic sense, on their part.
[1] https://qz.com/1344537/by-2020-suvs-could-make-up-50-of-us-c...