Because it's the first time in a decade the US has done it, and done it in a way that is significantly less expensive, paving the way for much easier access. It's a minor historical event in terms of human achievement since, as you said, we've done it before. But it's a major economical event in the history of space exploration, and historic for the potential that represents.

This is a big deal because a group making up a medium-sized private company with a private company budget was able to accomplish what a nation-state sized government with an unlimited budget was able to accomplish ~40 years ago. And if they can do it, then it won't be long before other companies do it too, which means that space travel will no longer be limited by political ambitions or realities.

This is the Apple II moment of space travel: when megacorporation giants were squeezed out of the market in a few short years by some dudes working out of their garages.

Imagine your same argument but comparing old computer modems to new ones. I dont get it why is a gigabit connection a big deal? I have my 14.4kps modem and I can download images just as good? ... Now we can do a lot more, for a lot cheaper, and the cheaper it becomes the more we can do in space. We could do mining, better satellites, colonies, better research.. Space is the limit ;)

I was thinking it seems a bit unfair to go on about how amazing it is while ignoring the Russian rockets that have been doing the same mission for years eg. https://youtu.be/erfXf08tuFg?t=3906

However watching that it's cool to see cutting edge tech rather than the 1960s style stuff. Also hopefully this is just a step for SpaceX on the way to Mars and beyond.

The big deal is what is now much more likely to happen in 10 years because of what just happened. People are inspired by a successful mission and that makes the possibility of future missions more real.