You dont need shoulder protection in airsoft though.
The interceptor is commonly worn with bicep protectors these days. IBA bicep protectors even have pals webbing on them for pouches, though only enough for something like a compass pouch or something.
The vast majority of pouches do not attach by velcro. In fact, i cant think of any pouch that attaches by velcro and velcro only. Even the 'swat' tactical armour carriers have snaps as well as velcro, without the snaps, the pouch is not likely to stay put. Most pouches attach via the PALS/MOLLE system these days.
EDIT: Looks like Tiger Tactical is working on an IBA cover with bicep protectors. Something to consider.
http://www.tigertactical.com/gallery...ducts/P4150001