Shackles were bad for combat because if I bring two friends and have five minutes to work something out there is noone in imperian past or present who isn't going to die. Its a licence for a free kill and that is dumb. There is no degree of quick reactions or smart play that is going to save a person in that situation. Personally I used to just doomworm because why bother.
Chains are actually (slightly) more balanced because 1 minute is somewhat more reasonable - this means if the people attacking you are incompetent you do have a shot at surviving. The problem is chains last too long - I have enough chain charges that I probably would not have ran out within 5 years of active play and I did not buy heavily into chain rewarding promotions. Shackles are a (very debatable) limited resource. Chains are a staple that superceeds every other hinder skill in the game.
Personally I'm opposed to mechanics like this in general though - I'm of the mind that you should have to exert some degree of effort to force someone into a fight that they have no mechanical recourse of evading. Its why I went out of my way to make greensharding me as miserable an experience as possible.
Making shackles/chains block exclusively special forms of travel is a superb solution, imo. It preserves the use against powerful artefact escapes (and skill escapes too, but that's probably fine) while meaning people will still be able to escape the situation if they play well.