Looking over the playoff rosters, it looks like there actually were a few Europeans playing in the ECHL last year, but you are right that there aren't many.
But, regardless, why would they come over here? It's one thing if they're an NHL or AHL team's prospect pool and just got recently demoted, but I can't really think of a reason why they'd come over just to play in the ECHL. Pay's not very good and the level of play is lower than many European leagues, so might as well stay home and play at a higher level for better pay.