The reason why EA doesn’t want the Sims Freeplay and the Sims Mobile released for Windows 10 too isn’t about avoiding confusion but to avoid that some simmers will play one of the mobile games instead of buying TS4 and its huge number of packs! The mobile games are meant to mainly be played shorter periods in busses, trains, schools and other places when simmers aren’t home. They are made as they are because they aren’t meant to be played for hours at home like TS4 is. So that way EA was able to release the mobile games without having to fear that they would steal customers from TS4.
EA has also always kept sidegames small such that people soon would return to the main game. This was true both for the Sims Stories games and for the Sims Medieval.