They did, though. The second emperor, Henri d'Flandres, crushed both the nikaeans and the bulgars repeatedly, and decisively at that.Strength doesn't mean anything if you don't know how to use it.
https://en.wikipedia.org/wiki/Battle_of_Philippopolis_(1208)
https://en.wikipedia.org/wiki/Battle_of_the_Rhyndacus_(1211)
https://en.wikipedia.org/wiki/Battle_of_Adramyttion_(1205)
He was also notably kind to the local hellenes, going head to head with the pope and his legates, countermanding orders by papal legates to close down orthodox churches and arrest orthodox clergy, and, apparently, involving the hellenes in the romanian government and overall treating them as he would any other one of his subjects, or so Georgios Akropolites, a greek and likely to have a bias against the crusaders, is known to have written.
In addition, henri, though by all accounts a highly proficient general, seemed to prefer peace and avoid war whenever possible, judging by his treaties with the nikaeans, and his marriage with the stepdaughter of the defeated bulgar king.
All that needs to happen is that Umberto di Biandrate be prevented from poisoning henri. When the nikaeans inevitably suffer from civil war between the Laskarids and Vatazenids, Henri may well pounce, and, considering his previous record, likely be successful in whatever campaign he decides to undertake. With a marriage with the bulgars, and a quite possibly defeated nikaeans, the Komnenodoukas are likely to be brought to heel, facing the undivided attention of the latin empire and it's most successful emperor.