I think a lot of it has to do with player skill(mine being relatively low), and the nature of the basetake.
I played a few years back, back before the days of the flag in town. I don't remember many people upping then either. Now if you don't shut the base down and/or take it quickly a 262 comes in kills your goons/someone strafes the troops, GVs pour outta of the hangers after 15 mins, and people up like crazy. Leaves you really with 2 options, deack and cap the field, or close the base. I personally consider closing the base a little more...I guess humane? And then you got reinforcments upping from nearby field to get alt,defend and goon hunt, GVs coming into town from adjacent spawns. It just becomes a mess at that point, becomes a possibly long drawn out furball.
When a 20 or 15 man mission comes in and an equal number up to defend, you're going to lose people to Ack, Manned Ack, Whirbls, getting ganged on, HOing, Ramming, stupid decisions and whatever else. The Attackers take 10-15 mins to get back and the defenders just reup. Your mission turns into a drawn out slugfest instead of a basetake.
I personally think the basetakes got uglier/dirtier because the defenders got uglier/dirtier.
My 2 cents, in my experiance.