IMO the reason objective gametypes aren't popular is because they aren't slayer.
There's a reason deathmatch is the most popular gametype in any shooter. A LOT of people don't like to consider things like flag reset time, flag juggling, bomb arming time, etc.
They just want to kill things.
A very popular FPS back in the day, RTCW, had pretty much 95% of the servers consist of one-sided objective gametypes as opposed to deathmatch. Granted, the developers built all of the original maps that shipped with the game with one sided objective in mind.
The problem with Halo is that they don't do objective right. It's frustrating, not competitive, and too much time is wasted.
From my experience in various FPS games (including Quake, CS, and ofc RTCW & Halo), one-sided objective games are far more fun AND competitive than double-sided objective games (like multiflag) when
they are done right. Basically, the attacking team that successfully completes the objective faster should be rewarded. It saves so much time and adds a new depth to the game. Strategy, tactics, and execution become more important than ever since every single second is vital. It's called stopwatching the game.
I feel like I will take the time to educate everyone on how to achieve a proper stopwatch mode by analysing the problems with Halo's one sided objective games.
Problem #1: Pointless final round
Take this 4-round 1-Flag game on High Ground (Halo 3) as an example:
Round 1: Team A caps the flag (Score is now 1-0)
Round 2: Team B fails to cap (Score remains 1-0)
Round 3: Team A caps the flag (Score is now 2-0)
Round 4: ...
Result: Team A wins (regardless of Round 4)
Round 4 is entirely irrelevant since it is literally IMPOSSIBLE for Team B to win. It is, simply put, a waste of time. I remember back in the Team Objective days of H3... if my team dominated the first 3 rounds, we would just let the other team cap in the 4th round in the interest of time.
The above game should end as soon as Round 3 is over.
Here's another example:
Round 1: Team A fails to cap the flag (Score is 0-0)
Round 2: Team B caps (Score is 0-1)
Round 3: Team A fails to cap (Score remains 0-1)
Round 4: Team B decides to not go for the objective and instead just pad their stats by spawn killing for the entire round
Result: Team B wins (regardless of Round 4)
Now a game like this is why I can understand people don't play objective. Who wants to play a game where the opposing team is spawn killing you until the time runs out instead of just playing the objective.
Ending the game after the third round in this case is the only way to avoid giving opportunities to griefers.
Problem #2: Pointless tie
Now, just say there is a 2-round 1-Flag game on High Ground
Round 1: Team A caps in 5 minutes
Round 2: Team B caps in 1 minute
Result: Tie
Why is this a tie? Team B clearly deserves the win. I mean, did they not cap in 1/5th of the time that Team A did?
Problem #3: Wasted time
Now for this problem, let's assume that 343 decides to fix Problem #2 and reward the faster team. Sweet, but there is still 1 remaining problem.
Let's use a 2-round 1-Flag game on High Ground as our last example
Round 1: Team A caps in 1 minute
Round 2: Team B caps in 5 minutes
Result: Team A wins (assuming the faster team is rewarded)
The problem lies within the second round. The game should end if it's impossible for Team B to win, don't you think? Therefore the time limit of Round 2 should be set to the exact time that Team A successfully completed the objective in Round 1 (if they failed, then just leave it as the default time).
So assuming it's implemented with that in mind... then the game would then be:
Round 1: Team A caps in 1 minute
Round 2: 1 minute passes and Team B fails to cap. Game over.
Result: Team A wins
Same result, except not even a millisecond of time is wasted!
tl;dr: Objective in Halo would be way more fun, competitive, and appeal to a larger crowd if they focused on improving the one-sided objective gametypes by rewarded the faster team and not wasting copious amounts of time.
Btw, first post here =)