Nobody had issues juggling in Tekken 5. Just the juggle capability of some characters weren't as good as other characters. This is no different than any other fighting game where some characters can combo better than others.
On average, bound really only adds 1 - 3 hits per juggle. What really made juggles last longer after Tekken 6 was NOT bound, but the changes to the float properties of the victim and addition of lots of moves that serve as juggle fillers.
What bound really added was improved oki for a lot of characters. The ability to spike an opponent at the end of a juggle to set up a advantageous oki situation was actually very rare before Tekken 6. It was a big part of the reason that Devil Jin was so good in Tekken DR, because he had fantastic mid stage oki which was INCREDIBLY rare back then. The addition of bound gives every character a universal option to set up a spike into an advantageous oki situation. This is why bound as a specific mechanic is needed.
If you remove bound and try to bandaid this aspect by giving everyone a spike move, then the juggle physics are going to have to be completely reworked, because as it is now, spiking an opponent without bound still makes the opponent slide out of range for anything meaningful. In that situation, the only characters with strong oki will be characters like Lars who has a spike option that moves him forward to negate the effect of the opponent sliding away. It'll be another Tekken DR Devil Jin situation all over again.
On another note that is unrelated to the quoted post, even in Tekken Tag 2, your average juggle is no more than 4-5 seconds. As usual, a lot of hyperbole comes into play when it comes to people complaining about juggles.