I think I know what your problem is. Football at the highest level has undergone a sea change in recent seasons, and the importance of a central defender's ability to be proficient in the possession game is becoming more pronounced. Yet folks still have very conservative views of what central defenders are supposed to be like. The game is constantly evolving, elite teams are becoming more diverse instead of relying on specialists, so in a sense comparing a central defender like Ramos with Baresi or Kohler is like comparing a deep lying, modern definition of a defensive midfielder in Xabi Alonso with Rijkaard or Monti - and then complaining about the stylistic or maybe even functional variance in their approach.
If you carefully examine 3 of the most successful teams in Europe through the past 5 seasons - Real Madrid, Barcelona and Bayern Munich, the number of times their central defenders touch the ball per game is almost as high as the midfielders through some of the biggest matches of the season. The best European clubs are putting a lot of emphasis on defenders who can help control the rhythm of games from the back, and help build up the offensive play from deeper areas. This trait is of utmost importance under a manager like Van Gaal who likes his goalkeepers and central defenders to be extremely comfortable in possession.
This is why he isn't likely to sign a keeper like Cech (if he was hypothetically interested in moving out of London), even though he might technically be the best pure goalkeeper available. Edwin Van der Sar wasn't the greatest shot-stopper or the most natural pure goalkeeper when he was at Ajax, something that has been well documented though the years. But he had the qualities that Van Gaal wanted in possession and organisational ability, and Louis along-with Hoek helped him become one of he very best goalkeepers around. Hence Van Gaal referring to him as the "manufactured goalkeeper". Ramos might not be as good of a pure defender as Kohler or Baresi or Maldini, he might not even be comparable to Godin as a pure defender, but as long as he functions well in Van Gaal's overall scheme, that's more than enough. Though somehow, people are having a hard time processing that simple thought. Is Ramos the final solution for our defensive problems ? Not at all. In Van Gaal's grand scheme of things, could he be a major part of the final solution ? Absolutely yes.
Also, the oft-repeated 'annoying' bit is based on a very specific set of personal preferences, and should't really be a great reason for not signing Ramos. Was Henry a pompous, annoying arse ? Yes. Was Pires annoying at Arsenal ? Yes. Was Costa annoying at Atletico ? Yes. But given the chance, should/ would United have signed them ? Absolutely, because at the end of the day transfer decisions should be made on more objective, performance related factors (unless Ramos has a record of going full Suarez, which he doesn't). If Ramos is available, he might be the best central defender we could sign (under Louis strict criteria which prioritizes comfort in possession). And that's including someone who is arguably the better pure defender in Otamendi (on the basis of one season in a major league mind, not the not conclusive sample size).