Finally, if you are a fan of "How I Met Your Mother," you know that Ted is recounting events from his 20s and 30s to his teenage children. Therefore, he liked to leave out certain parts of the story to keep it age-appropriate. He also liked to use metaphors when referring to things he didn't want to divulge to his kids, namely, calling smoking marijuana "eating a sandwich." In many flashbacks to their college days and one flash-forward, sitting in a high school hallway, Ted, Marshall, and Lily are seen eating sandwiches in a haze of smoke.
The same tactic may have been used to describe Barney's over-the-top behavior. And while he might have been someone that cared deeply about his appearance and, due to his career, wore suits often, the extent of his obsession with his tailored wardrobe very well could have been a metaphor to hide a much darker aspect of Uncle Barney's past that Ted wanted to shield his children from. Of course, this all depends on one very crucial element.
What this comes down to is what kind of narrator you think Ted is. If you believe he is a reliable narrator and he is shielding his children from inappropriate content such as drug use, then sandwiches and suits are metaphors to cover up that part of his life. Barney did turn to suits following a horrible breakup, further supporting the theory. If you believe Ted is an unreliable narrator, then it is possible that the over-the-top nature of Barney's obsession with his suits was one more way Ted tried to make him look bad. The whole point of telling the story (as revealed in the finale) was to get the kids' blessings to pursue Robin (Cobie Smulders) all over again.
