Umm, no, fully disagree.
You should work for every level you obtain, period.
And getting to level 2 is cake. 3 is not hard at all, and 4 is not hard at all, just takes a little more time. I would expect that same for each level afterwards.
But you want to start at level 10? How about Larian just give us God mode?
If you want to start at level 1, have beginner adventurers as characters and not vampires and chosen.
Astarion: not a full flegged vampire but a minion who was enslaved and tortured by his master until he was kidnapped by the ones that are diseminating tadpoles all around. Pretty sure a master vampire woudn't allow a toy he uses to please his own sadism to rise level [All things that came from the game back story of the pale elf]
Gale: he fuc*ed up the weave causing Mystral to abandon him, him to become unstable necrotic nuclear bomb who needs powerful artifacts to not explode, and he admitt how his meddling with the weave has costs him his might and his powers [again all in the game]
Wyll: he has a conflictual relationship woth his patron, furthermore said pathron has been kidnapped possibly by the culprits that are messing with netherese magic to make the tadpoles something able to resist the habilities of an arch druid and a powerful hag, again he complains how now, with the tie to his patron weakened, his powers are far from those that allow him to adventur and gain the name of Th blade of frontiers.
Laez'el: she is not special in anyway, she is a gith with due arrogance but we get that she is not so much when the githaky patrol is finally found, the leader of the patrol treats her like a low rank.
Shadowheart: her memories have been suppressed, what could made her forget part of her training [on her I don't know much because the way my toons act make her to close on hersef and not to open about her history]
The player character: it has a custom background so its up to you to decide why they are at level one.
From the facts above I don't get the complaining about the levels, nor from a combat point, nor from a narrative point of view. Indeed in both cases there's a solid case for the party starting at level one (in one case is how easy is to get to a level you can fight th ebosses easily, in the second case there are narrative reasons of why the companions are low level instead of powerful like the seasoned adventurers they are).