Sheesh stop the ranting about Tifa alredy.... It is called free market. There are so many mods about her because IT SELLS. It is evident that the market, that is, the people that puts money to buy mods, are in general, interested in her. That gives the modders a signal that, if they create a Tifa mod, it would probably make more money for them. If they mod a character that is lesser known or more niche, they would sell less and get a lower income of $.
On a side note, different modders give different approaches to their mods. For example Xey's HS2 Tifa comes with all her hairstyles, while HS1 Xyth's version has a cleaner face, but her expressions are not as great as 73's version on HS1.... and so on.