Towel Root depends on being able to crash Linux (the operating system underlying Android). That little excploit was patched in June. There are some pretty good people working on finding another exploit to root later devices.
(It's probably possible to "downgrade" your phone to 4.4.2, which would allow Towel Root to root it.)
And, yes, Samsung has caved nin to AT&T and Verizon to make the phones more corporate-friendly and less user friendly. For those of us who don't have to worry about the "upstairs office", Samsung is just losing customers. I don't want a phone that can play Candy Crush, I want a Linux computer that can make phone calls. (It's why my over the air update firmware is disabled, and I'm still at 4.4.2. I won't upgrade until someone can root a later version of Android or I win the lottery and can buy a phone that doesn't make Fort Knox look like Swiss cheese.)