I don't think there's anything wrong with having to work hard to convince a player to join us - that is not really the issue for me.
The key issue is, does the player not want to join for footballing, personal or financial reasons?
'Personal reasons' worries me. We have seen when players' families are not happy, it is generally reflected in their performances and commitment (see Cavani, ADM)
'Financial reasons' worries me. We shouldn't be throwing well-above market-rate salaries at players to get them to join. This is a recipe for disaster and breeds resentment and disharmony in the squad and/or creates issues with the wage structure.
'Footballing reasons' doesn't worry me so much, in fact, I'd be pleased if FDJs reason for not wanting us to come is he thinks he's more likely to win trophies and play in bigger competitions at Barcelona. That shows his motivations for playing football are in-line with what I would want in my squad,. I don't want players who will willingly join a weaker side, playing in lesser competitions, just because the money was good!
If that's the reason and ETH can sell FDJ on his vision, his goals and make him believe he can achieve his footballing goals at OT, then there's absolutely nothing wrong with that at all - it should be encouraged!