You nailed it. People don't get promoted for leading pedestrian projects, they get promoted for leading challenging, innovative, groundbreaking projects.
Sometimes tech reminds me rich, bored, stay at home SO's that are constantly redecorating their house. Not because they need it, but because they are bored and the next trendy design looks cool anyway.
It comes from both top and bottom. At the top managers want to justify their salaries to their managers so they always redesign / rebuild / reorganize, even if things work pretty well as is. At the bottom new programmers fresh out of college want to assert themselves. The best way to do is to propose that everything existing is old and shit and needs to be rewritten. So they volunteer of course.
