The lack of freedom was terribly noticeable in both 3 and 4. I really enjoyed picking and choosing which gang I want to take out first in 1 and 2. Not only does this help you get used to each area and the gangs territory by doing a bit at a time, it also was a great way to develop the side characters. Since each side character (Dax, Johnny, Troy, Pierce, Carlos, Shaundi) would be your way into each gang, you had an opportunity to help build other characters beyond the gang feud.
In 3, most of the gang missions are retreads of side activities to help pad a lack of content, so they don't have a storyline to begin with. So characters like Angel and maybe the guy with the weird voice (see? can't remember his name) weren't too developed because of this. It felt like Kinzie and viola were the only worthwhile new recruits. It doesn't help that in 3, I don't really care either way about destroying killbane or his gang because he's a loser and barely poses a threat. It's also hard to care about Loren and the Morning Star when you don't ACTUALLY see them kill Gat. But in 2, when Carlos is killed, it's something else, and gives your character all the resolve to put Maero's girlfriend in a car trunk, and have him accidentally kill her by running over it while he's at a monster truck rally.
On the other hand, the anti gang force in 3 is way better developed than Ultor. And it feels heavenly giving them their just desserts in ending where you bring war to their giant flying warship for killing your compadres.
The lack of gangs in 4 especially feels like a weakness. It no longer feels like a sandbox because most story missions are handed out one at a time. There's not much in the way of choice.