You won't after you meet Dolores Umbridge.
Okay, well, that's not precisely true. I've met Dolores, and despite her very best efforts, I still do like pink. But that is neither here nor there.
I actually think if I ever chose a Harry Potter costume to try, it might be Umbridge, for a couple of reasons. While I despise the woman, her costumes are pretty difficult to mistake, and they'd be a fun addition to HP costume groups. Also, they would teach me suit-making techniques.
I work in an office environment, and while we're not required to wear suits, I sometimes like to wear them all the same, just because they make me feel super grown-up and professional and empowered. Alas, because I only wear skirts, I have come to understand just how difficult it is to find matching suit skirts. Except at the Limited, which makes stuff that is beautiful, but only comes in the sizes models wear, and is usually so short I think the "professional" part of the appeal is lost.
I did manage to find a wonderful store called Kaspar which carried beautiful matching suits (pants, skirts, and even dresses all with mix and match coordinating jackets) but the nearest outlet is over 200 miles away.
So. That being said. Learning to make a suit would be worth my own personal time. At this point in my life I'm only interested in making costumes, not "real" clothes, so Dolores might be a good way to tuck suck skills away for such a time in the future when that proclivity would change.
If you've recovered from that first bout of nauseating pink, here's another:
While this is not a suit cut I would wear, it nonetheless uses suiting fabric, special pockets, cuffs, etc.
"Suiting" is, quite simply, a fabric used for suits. It's usually woven and has a very nice lie. Tweed could conceivably fall into this category. Do a search for "pink suiting" and you'll get lots of horrific Dolores choices such as this.
Vogue 1269 has a good short jacket pattern for Dolores. I'm also very fond of Vogue 1237 for that very "buttoned up" feeling that Dolores expresses in her manner of dress. This Butterick pattern (5690) has an amazing coat that could work. Really, there are endless mix and match possibilities!
Don't forget to take your Pink Overload protection pills, though!