So now you need to add a level shifer increase the number of mistakes and the risk of ruining your board. Your solution makes life of hobbyists less enjoyable IMHO.
The GPIO are not level shifted in the board you link.
I think the suggestion is to make an electrically compatible Uno board by incorporating the level shifters onto the board. The end user wouldn't have to think about them because they are already there.
Of course I don't mean I expect a beginner to get a board made so that they can use a surface mount level shifter for their beginner project.
My question here is why the weird approach? Why have two MCUs on a board, and have the one that the user interacts with be the technically inferior one?
Why not just make a better version of the ESPRIT? Just add a level shifter to it, and there you go: form factor compatible, 5V compatible, and more powerful than Arduino's not yet released project. And probably cheaper to manufacture than the two MCU design they came up with.
And yeah, you can use exactly the same IDE and API for the ESP32.
Renesas had been trying to get into Arduino market, previously with Gadget Renesas efforts. Arduino is expanding more into (over-bloated...) industrial control applications for heavy industries. There, I would assume, the both parties saw aligned interests to have a Renesas chip in the center of a new Arduino(maybe ARM might be in it too).
Performance must have been a non-issue, they make everything from timers for rice cookers to custom ISA smartphone SoCs. It must have been just an option that is good enough, easily available and comfortably low-tech to let to an enthusiast with an SEM in his basement.
Though does Arduino really amount to something measurable to a giant like Renesas? And I presume that Arduino plans to keep the IDE and API, so not like 99% of people would be learning anything about the details of Renesas' chips.
Renesas/then-Hitachi H8 and Microchip PIC were popular in Japanese EE colleges and Universities. The H8 was always a bit too advanced, more popular in more niche robotics than plain EE, and must have been not too important for Renesas. But the latter was blown away entirely by AVR as Arduino came around and created a whole hobbyist industry.
IDE and API won't be issues, it's just bare C/C++ and APIs are just extra standard libraries. But the popularity of Arduino and ATmega328P/ATmega32U, its expanded talent pools, etc must be somewhat tempting and potentially-vital-looking for Renesas, while also not too tempting nor threatening to make substantial changes to its operations and focus on over the counter chip sales.
Why would you need to add a level shifter. Almost every single i2c or SPI component I've used works just fine with the ESPs 3.3v or is 3.3v to 5v compatible.
The GPIO are not level shifted in the board you link.