I totally agree with you that most people should not implement their own XML parser, much less an Excel importer. But I'm grateful to have the luxury of being allowed/able to do both.

The specific choice I made doesn't matter. What matters is the process of deciding trade-offs between one approach and another.

My point is that the OP advice of "do the simplest thing that could possibly work" doesn't help a junior engineer (who doesn't have the experience to evaluate the trade-off) but it's superfluous for a senior engineer (who already has well-developed instincts).