How valuable is that "tax-free compound interest" really? If you have a relatively reasonable retirement income the current laws have you paying no federal tax on dividends and capital gains in taxable accounts. Sure, laws may change or your income may go way up for some reason, but under the current state of affairs I just can't attach a significant number on the benefit of shifting $6k/year from taxable to Roth. It's worth something, so I'll do it if I have the opportunity, but it's not going to dictate how I spend my time.
You're FI. You don't need the money. If you're going to go get a job, find some non-monetary reason that you want to do it.