I think GW2 shines the most in groups of 5-10 players. That's why I think objectives and encounters should be designed in a way that it makes little sense to allocate more than 10 players for each objective. I'd say if we could split up champs in Open World into champ groups spread around a bit, and change WvW so there are more smaller objectives on the map we could reduce visual noise, reduce importance of zergs and flatten the learning curve between low-end and high-end pvx.
Note: I am not opposed to champ farming or huge open world bosses, but think both could be expanded and improved upon given this game's popularity.
What do you think?