There’s a big strategic difference between Superflex and tight end premium. Superflex requires or at least allows an extra starter at the quarterback position. Since quarterbacks score far more fantasy points than any other position, it almost always makes sense to start a second quarterback in that slot.
On the other hand, tight ends score the least of all the main fantasy positions. It’s possible to use a 2TE format to force fantasy owners to value tight ends. However, there are barely 12 fantasy-relevant tight ends in the league, let alone 24. Forcing people to start 24 tight ends every week isn’t a fair or viable fantasy format, in my view. It introduces even more randomness, as the bottom tight ends are wholly touchdown-dependent players.