1. MMOs just gravitate to a monopoly because of time and gw2, unfortunately, is more of a time sink (pve) than gw1, so its hard to draw people in who play wow. Its hard to play gw2 and wow at the same time, but the same cannot be said for playing wow and gw1. As long as wow is around, gw2 can't kill wow unless it is downright better in all aspects and has better marketing.
2. weapon system is cool but is far too limiting. in gw1 you choose 8 skills from two classes and you can make whatever you want. with weapon systems you basically get limited to few skills you personally get to choose, and you also forced to take an elite skill (not a problem, but you get far less choices for elites where as in gw1 you could pick any elite from 2 classes. This was SUPPOSED to be balanced by weapon choice, but unfortunately not every weapon is equal and some are required.
3. lengedaries imba. in gw1 you could get any max dmg weapon and mod it and it would be the best you could get. skins and armor were cosmetic. with legendaries, you have to grind for the best item (pve wise), which is cool but you don't get to pick a skin, which is just not guildwars at all.
3a. counter argument would be, "oh well if everything is cosmetic than nobody will want to progress to get anything, they'll just be content." purely not true, how your pve character looked in both pve AND if you could mod it to be useful in pvp was so much fun and so many people spent absurd money/time to make themselves look cool/original. If 60% of armor looks like dirt and the other 40% are expensive or take time to make, people will take the time to make themselves look good, and because your dirt was functionally the same as the cool looking armor, you didn't have to if you didn't want to.
1. no healers is fine, but no prot monk? a design in which you have reactive and preparatory spells, and the less reactive casts you make the more energy you and your monk partner save? best healer design in mmos, period. its not a problem they dropped it and healers, its a shame.
1a. no healers is also a bad marketing choice, imo. I personally prefer healers and can't find the time to play gw2 because i outwardly don't enjoy any of the classes to spend my time on playing one.
2. maps. cap point out the ass. i can't even complain how fucking boring it is to stand on a node game after game. HA had so many different map styles and there were so many different gvg maps your comp had to be able to address in gw1, now you have cap point.
3. cd length is so atrocious. ill call it the reckful argument, and games should realize it by now: do not make 2+minute or even 1.5+minute cds. MOBAs: longest cd I can think of is blackhole in dota2, and that shit is fucking imba, but most cds are 4-20 secs and ulties 1-1.5mins. gw1: most abilities were 1-20 seconds, minus some spirits etc? now we have 1min cd utilities and 3 min cd elites, seriously boring.
FORTUNATELY, anet is really good about making their games improve (nightfall and eotn were much improved over an already improved factions, and gw2 contains many combat changes that are 1000000x better than wow). I think they'll improve, but it will take time. All of my complaints can be fixed, except maybe the class preference, which will just depend on what they add to the game.
tl;dr- gw2 improved in someways, but is just not gw1, and they dropped a lot of really cool parts.