Once they abandoned the typing interface, Sierra games lost their appeal to me.

Exactly. I was so upset when they did that I just stopped playing. I didn't mind the “point-and-click to move” use of the mouse when they added it, but taking out the idea of having to think about what do to with what objects just killed the games for me. (in addition to the loss of being able to type in swear words to see what it would spit back out at you; or commands like “take off your clothes” in Police Quest and having the character do it and lose the game). In fact, I don't think I've played an "adventure" game of any type since.