The release clause for a player like Haaland is projecting to be, is astronomically lower than he will command on the open market. If you somehow believe Manchester United are going to be strong armed into signing a player and allow his release clause to be so low that any club with ambition can trigger it, you are absolutely out of your mind.
First off, the optics are absolutely horrible. The players and agents can dictate the terms on when a player can leave a club. It opens up a pandoras box where other players and talent will demand the same, as to remain in complete control of where they play at any given time relatively speaking. For a club like Manchester United to be forced to let their potential golden boy leave for what in todays market is the price of a good midfielder.. That is absolutely never going to happen. You automatically devalue the clubs status if you allow clauses like that.
Dortmund accepted the clause because they know very well they are a selling club. They sell players they want to keep frequently. Every time they put up a CL quality team on the pitch, Bayern München or some European club with financial muscles simply swoop in and buy their players. Compared to MUFC, Dortmund is poor, and Ill get back to why that matters. As this entire saga has nothing to do with sports.
Mino Raiola and a couple others have in recent years managed to create a new structure in player transfers, where agents earn insane profits from player transfers. The norm used to be clubs agree on fee, agent gets a reasonable fixed fee, end of story. Now you have these superagents that commission incredible sums, and actively move their players between rich clubs. All while increasing the players wages, and their own cut of the transfer fees. Allowing a lowball release clause hands control of the players future over to the player, and leaves the club helpless. If a bidding club offers the release clause, they have no say in the players future. You are essentially asking the clubs to start allowing players to dictate contract length, not vice versa.
For the clubs, this is all about asset management. The value of your assets dictate everything from share value to potential bank loans, loan obligations what have you. A lowball release clause potentially devalues the asset. That is one part of the consideration. Clubs have very different standings in international markets and they have a certain status to uphold to attract business. One of those is how the club is perceived. Allowing yourself to becoming a selling club like Dortmund, who internatonally is a pretty small club compared to Real Madrid or even Arsenal, devalues the whole franchise.
The other part is the precedent that I've already mentioned. You allow one, more will come. No one wants a situation like that.
Now: Signing Haaland to a release clause in a vacuum, means nothing. Its one player that we can lose for under 50% of his value in 2 years. Maybe. In a vacuum, this isnt a big deal. The deal becomes important when talent number 2 wants the same clause. And player number 3. And player number 2349. If artificially low clauses become the norm, club lose all control of their assets longevity, and they never will or should allow that to happen.
So the arguments for this?
"Oh ArE YoU AFraiD hE wILl LeAvE??" - No. But you don't want a summer transfer window where you have to replace CR7 because Real Madrid triggered his release clause in August and good luck finding a replacement.
"JusT siGn HiM TO a neW cONtracT" - No club will play lottery with a incredibly valuable asset like that. This is never part of real life, and will never happen.
"hE reJEcteD the ClUB L0l l0sEr - signed, Manchester United fan" - That might be, I don't know what happened and neither do you. But we do know that the release clause around £60 million is real, and that makes the player signing here a non starter to begin with. For most top6 clubs in the big leagues, the release clause is Christmas Morning for clubs looking for a player like Haaland. It's like discovering a Bugatti Veyron hiding behind the "Everything 70% off" in the discount shelves at Walmart.
"WE COULD HAVE USED THE PLAYER NOW ARE YOU RET****D" - Go wash your mouth!
Also I agree that what you are describing would be the dealings of a top club if maybe not their only way of doing business. The question is whether United is that kind of top club right now. I really don't mean to knock them too much, reputation wise and financially they definitely are but over the last years of a sporting drought it seems like the perception may have shifted a bit. The club seems to struggle to attract the players they need (which may of course be down to incapable management and not club standing with players but then again one definitely influences the other).