As I recall, it was determined by most that on the 2017 MBP, it was not worth to upgrade to i7 from i5 on the 13" model. Some called it Intel scam. How about on the 2018 13"? Is it worth to upgrade from i5 to i7?
I take everything I read with a grain of salt. You'll have so many buyers who can't afford the upgraded processor, and many who can't afford the upgraded model, who will trash the change and the higher specs. There were so many people on here who bashed Apple for throttling last week, and look how that turned out for them.
Think of it like a car. If you're considering a Mercedes S-Class, you'll always have opinions about how leather seats are too hot and cloth is better, the paint on a Toyota has more coats, and the engine is made in the same plant as Hyundai. So, there's no point in getting the upgraded Mercedes, correct? You're wasting your money because it's not a better car and you can get the same thing for less, right? Not saying everyone does this, but I've encountered enough of these types to know to watch out for them.
The i7 is better than the i5. That's just the way it is. Even if it's "marginally" better in someone else's eyes doesn't mean it won't be much better in yours. Perspective is changed by the value of a dollar to the person. It's not worth it to the guy making $20 an hour, but it probably is to the guy making $100 an hour. Companies like Apple and Intel can't charge substantially more for a product that's the same as a lower model. If you think they do, I can bet you have cloth car seats and use generic paper towels.
When I made my decision a few weeks ago, I decided to get as much computer as I could reasonably afford and make use of. I usually upgrade RAM first, then processor, then storage, but that may not fit your needs. Either way, upgrading storage instead of RAM or processor is crazy to me. Storage can be expanded. CPU and RAM cannot. And next time you want to upgrade, you'll have an easier time selling an i7 than an i5. Macs hold their value so well, I don't even worry about the cost for processor or RAM. I'm maxing it out and I'll sell it for 3/4 it's original price when the next model is released, and buy another one.
Good luck!