This "lowest rate available" is kind of useful if one is flexible or willing to switch hotels in the middle of a trip. For example, I find in NYC that it is not always true the most expensive nights is the same night for all properties. So sometimes, one can save a little by doing a hotel shift in the middle. If the website only shows the lowest total cost of a stay, one may not realize another property have lower rates for a couple of the nights.

This is useful if one have difficult clients and need to stay below a certain dollar amount per night to avoid questions.

I also find it useful by expanding the dates of a trip (like if I have a two or three day trip but instead ask for a rate quote for 5 days) to see if I can lower the cost by coming in on different days than what I originally had in mind. The lowest rate available let's me see what is possible savings If I can be flexible, I find that sometimes it may save a couple of hundred dollars. Especially for NYC where room rate can be $170 for one of the nights and $350 the next night.