1) 4 vs 8 isn't just about today. You have to consider people use Macs for years. Think about what your apps require of your computer in 2020. And also, think about what OS X upgrades will require over the years.
2) you can never change the RAM.
3) you have no options if you need more RAM.
That's why people tend to choose the 8gb RAM. It's not that expensive, either, usually about $100 more.
Storage is a different issue,
where 1) they charge $200 more for more storage.
2) you can install a bigger SSD later (for less)
3) you can get external harddrives for big files at 8 cents per gigabyte, while the extra 128gb SSD costs more than $1.50 per gigabyte.
For browsing and video, 4gb is definitely enough. But for gaming on a virtual machine for example, not just today but also in 2018, I'd definitely try to scrape together $100 and get the 8gb version. Your resale value will go up a bit, too, as f trying to sell 4gb in 2020 when you want to sell your Mac is like trying to sell a Mac with 2gb today.
I think with your usage you can get away with 4gb though, as long as your games aren't heavy, but it's a risk.
