Loans are a way to have a bigger squad without having a bigger squad. Also, they are a way to put younger players to play, when they don't have a place to play in the bigger team.
This may be either good or bad, just depends on how it's implemented and used.
- Does it count for the squad on the original team?
- If a player returns and does not have a place in the squad?
- Does it increase the squad on the receiving team? This seems obvious to me that yes.
- Who controls the training? I loan a player but want to control what training the player gets.
- And what if the player does not play and receive training, is the original team penalised and the player does not evolve? For me that could be an option, but I'd say that the original team should choose the training type from the receiving team's coaches.
About the first question, it could be a new infrastructure, which allows you to be able to loan players, have a limit of loanable players (1 to 5, for example). When a player is loaned, he goes to that squad automatically, and when he returns to that squad until he is moved to the main squad (when there's a place). Players on that squad can't play on your team (including after return).
Just a few ideas about this. But I don't think that's a good thing for the game, as it gives even more power to the stronger teams, despite allows smaller teams to play with better players. It also reduces the transfer market.