For me equipment has to cater for Time on Water (TOW), I only have a budget to buy second hand sails and boards, but will buy new bases, booms and masts.
One of the things that killed the sport in the mid to late nineties, was that equipment got more and more technical and less & less accessible to sail, so
less TOW, at least the new developments in windsurfing are all about equipment which give you more TOW. I was a sceptic about the wider style boards, but have to admit I am a convert because they = more TOW. So if you have an old skinny board and don't get much TOW then a new or good 2nd hand wider style board would be highly recommended.
Durability is an issue, so I geuss that would be a factor in buying new, something that's gonna last like an ezzy sail.
I also think there is enough individual differences amongst us all for people to make their own decisions about how they wanna spend their money and whether they want to update to the latest gear every year (If they can afford to and don't harm anyone, then goodluck to them , I'm only slightly jealous

). I
certainly don't think there is a need to go new every year, the 2nd hand market is full of good equipment at a variety of prices.
that's my thrupence worth!