Today, 40sat/byte will include your transaction in the next block.
So will 5 sat/byte, and often 1 sat/byte is even enough. I wouldn't call 40 sat/byte "low", you're highly overpaying if you pay that much.
I want to add 3 possible reasons to bob123's list:
1. Fees went up so much because wallets with "automatic fees" were competing against eachother. They all tried to outbid others, which resulted in higher fees, while we were all still waiting. I've seen many threads where people complain their 400-600 sat/byte transaction was still unconfirmed after a very long time!
The "recommended fee" was quickly not high enough anymore, because all transactions after yours would have a higher fee.
I've also seen Bittrex pay thousands of dollars in fee, up to 5 times higher than needed at that moment, to prevent their transaction from getting stuck.
Back to your original question: it actually took quite a while for my Mycelium wallet to lower the recommended fee. It felt like it was waiting for other wallets to lower fees too.
2. At the peak of fees and Bitcoin price, miners were taking $40 million per day in block reward and fees out of the Bitcoin ecosystem. That drain of money needed a huge inflow of new capital to be sustained, and that clearly ended (at least for now). If less money flows into Bitcoin, there's also less available to spend on fees.
3.
Blocks aren't full. Even though at least one mining pool rejects transactions with less than 5 sat/byte fee, there's no need to pay a high fee if you don't have to compete against other Bitcoin users.