It kind of sucks being a rogue in the game since you get 2 other people that are rogues
If you are a fighter, there are 4 other fighters (Sten, Alistair, Dog, the dwarf, forgot his name. Also, there's the "secret character", but then you end up losing one of the fighters).
If you are a mage, there are 2 other mages (Wynne, Morrigan).
If you are a rogue... well, you've got that one nailed.
So it seems to me it doesn't particularly suck being a rogue - all other classes will give you duplicates, especially fighters.
Different mix of people will rely on different tactics. If you have your tactics all smoothed out and don't feel like experimenting or figuring out new/better tactics, then there's no point, really.
You can, alternatively, just let your party remain as is now. If you decide to give it another shot as a different character, you can try a different mix then. I've played it through using a mage (1st run) and a fighter (2nd run). I enjoyed the mage more in general, but the fighter was good as well. What's nice with being a mage is you can specialise in area of effect spells, have wynne do the same, and morrigan as well (her shapechanging is crap, so best to ignore it). When you've got two or three mages, you can have one case earthquake, another cast blizzard (or was it called ice storm?) and another cast fireball, then the blizzard fire counterpart - you get the idea, the enemies spend most of their time tumbling down and getting frozen, all while taking damage to all those Area of Effect spells. Most weak creatures don't survive, and the few that remain won't survive the next onslaught of your mages (lightning, ice/petrify + stonefist combo, etc), or they might not even be a match for your tank/s.
Arcane Warrior + Battlemage + Spirit Healer (for rez) ...
Hehe, yeah, I kinda hated being an arcane warrior - it just seemed to make the game so imbalanced in my favor - being a heavily armored mage that takes very little damage, carrying around 99 pcs of all kinds of lyrium potions... and of course, you've got party support as well (and if you make morrigan and wynne arcane warriors too...). Of course, I dressed up my mage with the best armors and massacred mobs by myself, just because it was fun to see.