Why Was Gangplank Reworked?

I know Riot reworks champion to update their kits or make them easier to balance, so I want to know what Riot thought was wrong with old GP.

I started playing him about 2 weeks before he was reworked not knowing he was about to get said rework. I love old GP, but the rework wasn't good to me, I actually disliked it so much I returned him. I know if GP hadn't been reworked he would be one of my most played champions right now, and it makes me sad to think what could've been.

I don't see how his rework made him better. It seems like the rework just took a balanced champion and made them much harder to balance.

Because I'm in a very similar situation right now. I played Syndra when she was on free rotation a few weeks ago and I loved her and couldn't believe I hadn't played her sooner, but now she's being changed and I'm afraid it's not a good change QQ If I'd known about her rework I never would've played her and gotten attached, and I don't see anything wrong with how she currently is.

These are 2 champions that I thought are really fun, but are getting reworks right after I discovered my love for them, it's frustrating.

TL;DR Why was reworked, and why is getting reworked?