Why is the maximum row height in Excel 546px?
Solution 1:
For the same reason as "640KB is more than enough for anyone!"?
I.e., they probably needed a limit for their view renderer and this was chosen arbitrarily but seemed "big enough" at the time.
By the way, 60 * 546 = 32,760 (8 pixels to spare) and 120 * 546 = 65520 (16 pixels to spare) so I suspect that was the arithmetic that drove that early choice.