Ya in the first Baldur's Gate when you travel towards the Cloakwood you are treated with a short cut-scene of a Wyvern flying over your head carrying a cow off to be snacked-upon!
My back of the envelope tally in one mid-level campaign is that ~25% of all encounters involve a large or bigger creature with Improved Grab. Any DM who likes non-humanoid shaped monsters is going to give you a steady diet of muscular opponents with Improved Grab. Even some bipedal opponents can have it.