That goes against the design goal of their multi player to be honest, they wanted fast and furious action, not sniping wars like some other games turn into. I don't know which game you are playing, but there are zero maps you can grenade spawn to spawn, sniper sure but not grenade.
Grenades and noobtube both worked quite well for that. Countdown S&D for example is a map where I remember games usually starting off like that: 3 people of each team noobtubing across the map in the approximate direction of the enemy spawn which led to a lot of time for ordering pizza, making coffee, writing novels.
On Backlot this actually worked with grenades as well: a few steps away from the spawn and knowing the approximate flight path of the grenade, you could lob your explosives straight into the enemy spawn. Also, both teams had cars close to their spawn so a nicely lobbed grenade would usually result in a number of early kills.
I've been playing CoD4 for several hundred hours online and had a fairly good time, but still think it's been a severely flawed game. In particular because not even these small maps and the fast paced gameplay effectively countered the camper mentality of a major part of the playerbase.
I think the MP maps were some of the best I've played since the quake days, they worked perfectly for the size of players they anticipate (mostly 5 or 6 man teams, not 16-20 a side).
That appears to be a competetive setup. The vast majority of pub servers I saw had at least 20 players per server, which, in my book, is at least more entertaining than the sneaky shit that's going on with less players.
The big downfall of both Activision companies is that they don't support the community as well as other games, especially Treyarch.
I agree that Treyarch did a very bad job at promoting and supporting their game and community.
IW did a lot better in my book. Charlieoscardelta.com was a pretty good community site - if you managed to avoid the forums that is.