A bit overly pessimistic to presume the adjustment period to wearing a lid will take 2 years , isn't it ? Also ,how about just have a bit more by way of training/net sessions to quicken up the ( much shorter than 2yrs) adjustment period ?
Even for these super friendly/casual teams you are referring to , im sure they could fork out 50 quid for a cheaper helmet ,knowing they would get at least 5yrs out of it ? I know plenty of other sports that participation rates aren't jeopardized by the purchase of one more item of safety equipment .
Basically , i think it just comes down to ' you don't know how easy it will be until you give it a good go' and old dogs not wanting to learn new tricks etc.