http://www.thesportsdoctor.com/hiddenthumb.html So it's essentially tradition and the almighty dollar. I read an article recently about the "ideal glove design" for boxing, and the glove they described was basically an MMA glove with extra padding.
Educated guess here.... Boxing used to allow alot more wrestling/clinching. So when first used gloves they had a thumb to still allow you to grip with your hand. Then they got rid of the wrestling but kept the same gloves. Then they added the 'attached thumb' so you couldn't thumb your opponent (as easily atleast). And now it's just kept around for tradition, because that's how gloves have always been. I'm sure eventually we'll see gloves like the 'hidden thumb design' posted above get widespread use.
I've always wondered this. Before I knew I'd have said it was tradition. If it's not broken, no need fixing it.
i wish i had some of them gloves my thumb is a mess its a total different shape to my other one i cant move it nowere near as far back as my other and if i catch in sparring i go pale white and the pain is unreal and makes me feel sick
didn't know about those - btw ugly looking - gloves with no visible thumb... Of course I understand about the advantages, but I think there are also some moments when having a differentiated thumb may be helpful, for instance, to hold the ropes when entering the ring, or the belt over ur head in case u get one, rearrange the waistline of ur pants or adjust ur groinguard, or even replace the mouthpiece - not vital enough but something to think about as well I think