Since the computer cannot be upgraded later you need to think not just about today but for the next couple years. Based on my previous experience with Mac notebooks, you should be able to continue using this new MBA for at least 5 years. If Apple continues to operate has it has in the past 10 years, we will see 5 new versions of Mac OS and at least 2 of those will require significantly more RAM than the version before it. Your programs will also be upgraded during that time and they too will tend to require more RAM.
So while 8GB is sufficient today, will it be sufficient during the last several years you own it? My experience suggests not. I just purchased a new Mac mini and it has 16GB, not because I absolutely need it now, but because I expect I absolutely will in a couple years down the road.