Pressure can be a verb too, as exemplified by a Telegraph headline: "Blair to pressure Sinn Fein over new ceasefire". One imagines a few squawks from readers. Why use the noun when there's a perfectly good verb? What's wrong with pressurise? Too long for the headline, replies the hardpressed sub-editor, pointing out that the story itself says pressurise in its first sentence. Not good enough, say the squawkers; if you couldn't fit pressurise in you should have put press, which means the same, doesn't it? - "Blair to press Sinn Fein over new ceasefire".
I'm not sure that it does. Pressing a friend to join me for dinner is one thing; pressurising him (or worse, her) to join me is another, and begins to sound like harassment. The longer version is the stronger, and was no doubt the right one for what Tony Blair has very properly been doing to Sinn Fein. As for tennis stars, we expect them to be pressed, but if they're being pressurised, their coaches have probably been getting at them, or they're being goaded by teenaged fans.
I don't particularly like pressured myself, but I don't know why. No one minds such noun-into-verb formations as auctioned or conditioned or structured, or thinks of saying structurised, though I see from the OED that structurise does exist, meaning "to give a structure to something". This surely comes into the category of totally useless words, since it does nothing that can't already be done by structure. I detect no difference between pressured and pressurised, so it's hard to say which is the useless one.