Because it wouldn’t be tempting if it was the smart thing to do.
Don’t be tempted into thinking the first thing you come up with is the right solution. Sure, maybe it is. But for all you know it isn’t. There’s likely plenty of worthy alternatives to be explored, so go explore those before deciding whether or not your intuition was right.
Don’t be tempted into thinking the first implementation you write is it. The solution behind it may be good, but maybe your code isn’t. Have you tested it? Thoroughly? Compiling isn’t testing, even if for some languages it might as well be.
Don’t be tempted into thinking you’re not going to have to come back to what you made later. Even if the idea is perfect and the execution flawless, there’s always going to be changes further down the line. It’s inevitable. So make sure you throw future you or whatever other poor sap has to come in a bone by leaving notes and advice.
Don’t be tempted into thinking the above is going to save you from pain always.