I've never had an issue with day 1 patches. I recall when NWN came out, the day 1 patch caused quite a stir. Players bemoaning the state of a game that "needed" one. Games are programs, written in one language or other full of if statements, while/for loops, functions and mathematical operations. They are meshes, maps, sounds and textures. There well inevitably be issues in the code that QA simply can't fix. (One dev have a great statement on this. If you had 100 QA testers (hah!) each putting in 1,000 hours, that's 100k hours of testing time. If 500k players each played for 2 hours, that's 1mill hours. Players will inevitably find things QA couldn't.)
Add others have mentioned, games go gold quite some time before release. Now in stupid arsehole companies, they start working on day 1 dlc. In fucking arsehole companies, they remove content made before the game went gold and include it in the same bloody disc or sell it on day 1. A good company however, spends post-gone gold, pre-release time polishing and bug fixing further so that the day 1 experience is better for players and at no extra cost. The price of the full game should get you a full game on day 1.
For players with slow or capped connections, I sympathise but I'd rather a day 1 patch than fixable bugs.