Keep in mind that in WWII, the US built some very capable heavy tanks, but choose to keep sending Sherman tanks. The reason was logistics. Eventually some US heavies made it to Europe, mainly to test the support infrastructure.
There are some very good reasons to have a light tank like the Booker and that revolves around logistics, terrain and infrastructure. There are a lot of places that would not allow a tank as heavy as the M1 to operate as the roads and bridges would collapse. so a light tank that can support the infantry there, is worth its weight in gold. The US can easily sustain some light tank battalions and it's likley these will sell as exports to replace the remaining CRVT's and other older light tank fleets out there.