<smarmy arsehole reply>
Because everyone beats off to oldschooltrack.com/messenger rhetoric of "If it's not old, then it's not cool". Kinda like how if you have a brand new skateboard, it's not cool until you bash it up and pretend you can actually do nose slides down the entire hand rail.
Keirin bikes sort of branched off from that because they're still made like the old school bikes (street cred +1) and sort of formed their own little cult of 6'3" tall hipster anime nerds with too much money for 52 cm sized bikes (it's got that compact geometry, yo!) that are frankly technologically inferior in every possible way to bikes made since 1990.
</smarmy arsehole reply>
Fetishization comes in different forms.