I've had this sentiment from 1996 on. I worked for a company creating Internet materials for use in classrooms (Internet-on-CD, books, etc.). I remember seeing a "frog dissection" thing on a website and everyone seemed to impressed with it. Why? You'd click a gif, it'd run a CGI and deliver a new image. Just what you could do with actual clients, just slower, more limited, and lower resolution.
There's something neat about "X in Y" for some technical novelty (like emulators) but I don't get the excitement in general.
This has been stated a million times, and I'm not even a "web developer" like the majority here seems to be, by my take is this: not needing a client is the win.
There's a huge amount of value, as perceived by "users" of the services/applications/games, in not having to care about and install a specific client for each service/application/game.
That's why it's noteworthy when something that used to require a heavliy specialized client, such as a game, no longer does for delivering the same experience.
There's something neat about "X in Y" for some technical novelty (like emulators) but I don't get the excitement in general.