It is not uncommon for coaches and managers taking over at clubs in countries they have no experience of to ask for coaches and staff with a connection, history, knowledge of that club, division, area, etc. Not everything Steve Gibson did or does is wrong, or a calculated measure designed to undermine his manager or head coach. Maybe if Gibson was determined to make Karanka's life more difficult he would've personally stepped in and made him keep Hignett in his position?
The thing about signings - Karanka, Pulis, Woodgate et al know the situation when they take the job. The manager has the final say on transfers but sometimes recruitment may well be slightly more collaborative. If you don't like this way of working then don't take the job. Southgate said he wanted Alves, for example, but then changed his mind and let the club take the flak. He didn't come out and change his mind on, say, Luke Young though. Or Robert Huth. Nothing about Tuncay. Probably because they were good. You know full well that if Alves had rattled in 20 goals we wouldn't have heard a peep about recruitment.
If a manager joins a club and doesn't like the recruitment process then a)don't take the job or b)stand up for yourself and your principles and leave. Warnock did it himself if you remember, just in a minor way, just casually mentioning it was Woodgate who was pushing for Grant Hall and putting the deal together. This was when Hall had had a patchy start and then been out injured for months. He also said he said the club should do the deal last summer, after he'd been in the job a few weeks or so. Nicely covering his **** there. If he's sh*t it was Woodgate really, if he's good it was me. I did it. Like Akpom, who he definitely definitely wanted and then changed his position on after it became apparent he wasn't that good but then had to qualify again in the press. A lot of managers and coaches are just covering themselves.
Always make sure you mention the recruitment team or "other people's signings" when things aren't quite going to plan. Not when you get promoted, of course, or make the play-offs or win 4 or 5 on the bounce. Lost 2-0 at Huddersfield? The bloody recruitment team, Jesus wept. Beat Rotherham 4-1? I set us up just right, MY players were excellent. It's just newspaper fodder.