Since when did everyone start wearing wetsuits to go for a swim?

[An Gadaí]

I noticed this summer in the frigid waters around Ireland that a huge amount of people were out swimming wearing wetsuits. Is this just an offshoot of the surfing/kayaking boom or has everyone here gone soft?
I, for one, jumped in to the balmy waters of the Irish Sea sans wetsuit on more than one occasion and after about an hour the aching stopped.