You don't think others will start to demand more? It's not about what the club gives them, it's about what they want and what it does to their attitude if they're in a constant battle over wages. It can cause tension and unrest within the group and it's the complete antithesis of Klopp's dressing-room philosophy.
Of course that might not happen, but if it does then the repercussions are much more far-reaching than retaining the services of one player for the next few years, no matter how good he is.
It's a gamble either way, it's not a straightforward decision by any means, imo.