The Sukhoi 15 was considered by the Devs but not implemented.
It has had more variants than most of the mid to top tier planes and was a widely used plane in the USSR.
The Sukhoi line has a very large jump from the su22’s many models up to the su27 with nothing in-between it’s one of the largest changes I’ve seen. Straight from r60’s to r27’s. It is stupid and must be resolved!!
Passed for considerstion doesn’t mean its on its way, only that there is sufficient interest and information to add the list of possible future additions. It certainly not a case of being ignored.
It would be a completely new model, both airframe and armament, and these dont happen overnight. Its also a pure interceptor which traditionally dont fit well in to the WT meta, and its not like you can grind mods through ground pounding. So finding a balanced BR to drop it in can be difficult.
Of course it could be rushed through but that simply risks leaving users with a poorly modelled plane at a BR where it is either OP or completely uselss. Personally i would rather it be added when its viable.
To be fair pretty all Soviet interceptors were and are ignored. There’s hope we might see Su-15, Yak-28P and the “Fox”-family in the future, but Id keep my expectations low (ever more so with community here being adamant on “There’s no gameplay for Interceptors”)
Vehicles that have been considered by the Devs do not necessarily arrive in subsequent updates, it just means that the aircraft could be added in the future (a variant of the Rafale was considered almost a year ago already).