IMHO most players don't really want their PCs using many different weapons, they have an image of their character, which includes the weapon.
If a DM insists of throwing a flail on the treasure pile meant to be used character X, who so far only used longswords, he shouldn't be surprised if will be disenchanted/sold and the gain saved for buying the next longsword.
Even if character X actually can use each and every of bis bonuses/feats equally with a flail or longsword and the flail even has a higher plus.
Because character X only using longswords isn't a flaw in the system but how the player of character X likes his character
If a DM insists of throwing a flail on the treasure pile meant to be used character X, who so far only used longswords, he shouldn't be surprised if will be disenchanted/sold and the gain saved for buying the next longsword.
Even if character X actually can use each and every of bis bonuses/feats equally with a flail or longsword and the flail even has a higher plus.
Because character X only using longswords isn't a flaw in the system but how the player of character X likes his character