Tough pledging can cause "close bonding" within the class, sure... but at what means? The traditional pledging system seems to be all fear based, so you are scaring your new members sh*tless so they are forced to bond with each other.
That's great for the first semester.
Then once the pledge class becomes active brothers or sisters, you have the possibility of bitterness towards the active chapter. Yeah, they'll be bonded with each other, but you've stressed Pledge Class Bonding so much that you haven't really focused on WHOLE CHAPTER Bonding. Then you get pledge class rivalry.
I've seen it happen. It's not fun to deal with.
To me, "Bonding" doesn't happen over night. I don't agree with forcing a new member group to bond after 2 events. It it something that takes time. And if it takes more than a semester, well so be it. Not everyone can be friends.