The devs have never cited PS3 as a reason a feature couldn't be introduced. That is, and always has been, player speculation. In actuality, when the devs want to add a feature that PS3 can't support, they simply add it just to PS4 and PC, or give PS3 a degraded version. For example, the shiny floor effects, or the half-sized W Crosshotbar. It is possible that there are features that the devs wanted to introduce but couldn't because of the PS3 - but if they exist, it is not an excuse the devs have ever used.

As for speech bubbles, I see no value in them if they work like the NPC speech bubbles. If the NPC is moving around, those speech bubbles are just about impossible to read - and even if they're holding perfectly still, it's difficult. As for distractions from moving and emoting, you pretty much have to have the camera zoomed in close to appreciate emotes properly, and if you're doing that then you're in a low-key enough situation that it's not difficult to quick-scan the chat box.

Someone brought up boss mechanics being difficult to read out of the chat window - just what mechanics are those? Any attack with a cast time is going to show up on the boss's cast bar, which a player is generally keeping an eye on during combat. Some bosses have mechanics that they "emote" to the player, such as Chimera's Violet Eyes / Blue Eyes in Cutter's Cry - those are pasted right across the middle of the screen, as well as in the chat box.