While matchmaking obviously cannot give you perfect matches every time especially with the limited playerbase and because of the huge experience difference in veteran (players who just entered veteran from recruit and players who have played hundreds of hours), there are still a lot of matches that could be a lot more balanced just by swapping some players in each team. It usually happens when there is a squad involved where the team with a full lvl 50 squad gets additional solo lvl 50s and high lvl players while the other team has maybe one lvl 50. so its six lvl 50s vs one lvl 50. The match is obviously unbalanced and could be a lot more balanced just by at least putting the solo lvl50s and high lvl players in one team so they can face the full lvl 50 squad, instead of further strengthening the full lvl50 squad.
The gap between t3 and t4 depends very much on the ship and the OBs that you have unlocked already. The gap between t3 and t4 artillery cruisers is not very big. T3 tacs and dreads can also be quite effective if you have GetMyGoodSide and Retaliator researched, thats a big "if" though. T3 destroyers and vetts will have a hard time. They both lack good offensive modules to compete with fully geared t4s and therefore they will have to play more as a support role or try to face other t3s.
I too think the grind is okay, however I usually play to win and not to grind so it might not feel that bad for me because I just don't care that much. However, while the average time for a new ship might not be that much, its the distribution of time you have to play each ship that makes it feel like an eternity. You can probably get from t1 to t2 in 2-3 games (even if you are new to the game), while you need dozens of games to get from t3 to t4. That combined with the huge experience gap between different veteran players and also difference in researched OBs/ships/modules makes it feel like you are permanently underpowered. I can see why it is very painfull if you are a new player in veteran and you are permanently on the bottom of the scoreboard and losing many games and therefore the grind will feel much worse than it is.
ship XY is overpowered;
I agree that ships in general are not overpowered, some OBs and some modules are though. There are also many modules that are completely underpowered. It also depends how many ships use a specific module, e.g.: one dread with armor booster pulse is easy to beat, however a healball with 2-3 dreads spamming armor booster pulse all the time is very difficult to beat as every ship in their group will permanently have huge amounts of damage reduction which will also effectively increase the healing output of the healers.