The bicycle industry just wants to keep selling you new stuff you don't need in order to get hold of more and more of your cash - it's as simple as that. When the market was saturated with drop bar sports bikes, in the 1980s, the industry started pushing rigid MTB's, or ATB's as they were originally called - often heavily influenced by old roadster frame geometry. Once everyone had loaded up on rigid frame MTB's and saturated that market, then they started pushing hardtails and full-sus bikes, and increasing the wheel sizes along the way to accelerate the frequency of the bike replacement cycle. More recently it's been "gravel" bikes, i.e. road bikes that actually have some tyre & mudguard clearance - a bit like the typical non-racing sports/touring bikes of the 70's and 80's did as a matter of course, but was considered normal! The whole name of the game is to convince cyclists that the bike they currently have is soon hopelessly out of date and therefore they absolutely MUST go out and buy whatever the latest thing they and the sycophantic cycling magazine media decide is a "must have". If you stand back and detach yourself from all this industry-driven marketing hype, you can see it for the BS it really is. Bikes do NOT need to replaced with new bikes every couple of years; once you possess a bike or bikes that do the job you require of them, they can last as long as you maintain them to last. Most of my bikes have had at least two owners, are over 20 years old, and are still every bit as useful as they were on the day they were built.
I've ignored the fad for 27.5" then 29" MTB's, ignored front or full suspension, ignored carbon fibre, ignored aero frames, ignored 1 x drive trains - yet strangely enough my old "outdated" machines still manage to get me everywhere I want to go on them without any fuss and probably with a lot less maintenance headaches than a lot of much newer stuff. We like poking fun at women and their shoe obsessions, yet a lot of male cyclists are far worse fashion victims concerning their bikes & the kit that goes with them, than any woman is about clothing.