My recollection was that GRUB when in graphical mode looks readable. Maybe I'm misremembering. The systemd-boot menu was definitely far too small and there was bug that was basically closed with "it's the firmware's job to give us a usable text output protocol".
Effectively, as shitty as the legacy PC-BIOS boot protocol was, it did at least allow open source software to jump in early and work around the gaping deficiencies in the vendor's firmware. UEFI has effectively replaced all that with a proprietary boot process. The vendor is now in complete control; want a usable text console, or to access the firmware via an external monitor? Vendor doesn't give a shit. Want to access the boot loader via the serial console? Oh you must be an enterprise, let me direct you to our sales staff who won't give you the time of day unless you've got £thousands to drop into their pocket.
Don't get me wrong, I'd love to replace GRUB with systemd-boot, but these are very real impediments to me ever doing so.