I'm so glad you are a precog and know that the massive mining infrastructure will be satisfied with fees when bitcoins stops being issued.

IIRC fees rn are a microscopic percentage (1%) of what miners make and by November, 95% of the 21 million bitcoins will have been distributed already.

Having a tail emission is also good for something called replacement. The concept that as time goes on, bitcoins will become unspendable. A tail emissions would not even "inflate" the supply if it matched displacement of burnt or lost coins. Think of a mechanism that would help the actual economic amount of bitcoins to not indefinitely fall at the same time that the value is rising. Not to mention that it provides a stable income (that is actually deminishing over time as the emissions will continue to be a smaller and smaller percentage of the overall amount of monero in circulation). If the tail emission is 1 monero, that 1 monero gets smaller and smaller as a reward over time as the total amount of monero grows...

tldr; Satoshi is not God. He was not perfect. Bitcoin isn't a discovery it's a synthesis of preexisting technology and it needed to be refined after launch. Unfortunately we're at a point where even as problems become apparent it will become increasingly difficult to fix them through consensus changes to the protocol. So IF the lack of a tail emission becomes a burden or misjudgement or causes severe economic or security trade-offs when the last of the 21 million bitcoins are emitted, there's not a lot we'll be able to do to rectify or remedy it.

I was skeptical about it as well (tail emissions). I recommend listening to anything Monero related on The Watchman Privacy podcast. It's a gem.