I’m going to take your advise and “hold onto” the one I just bought (unopened) through Thanksgiving. “If” the 2018 similarly spec’d model gets a good sale price, I may consider trading up. Luckily, I have another laptop I’m using now and don’t need to rush in setting up the new MacBook Pro.
To your question: Personally, I’d say it’s not worth the $500 difference given your use case. Honestly, I’d think that any of the 2017 13 inch MBP’s, the latest 12 inch Macbook or the new MacBook Air would work very well for the basic functioning you described and they all come in a small/light form factor....if you value that. I had the original 12 inch (lowest spec’d) Macbook when they came out. I bought it for my wife to use and I ended up using it for almost everything (except photo/video editing, etc...).
For me: I had a 2012 RMBP 15 inch that I used for a few years (8GB RAM, 212SSD, i7): I used it for work (Consulting) and had Paralells running on it so that I could also run Windows, also Lightroom for photos, Microsoft Office products (Excel, Word, Access etc..) and it was fine with the excption that I was taxing the 8GB RAM from time to time and had to manage the storage a bit. My use case with this new one is not much different except I also use Final Cut Pro X now for video editing. But still, the one I’m getting is probably overkill for how I use it....I just like to have a little “headroom”! If I were not doing these things with a laptop, I’d be looking at more the Macbook, MacBook Air or MBP 13 line for sure.
Maybe get one from B&H now if you’ve got your eye on one that’s a good value and hold onto it over the holidays to see if a better deal comes along!