During the Treaty of Paris, Spain originally wanted to give the USA just Mindanao and the Sulu Islands; or just a military base at Manila; some in the USA said that the US should only grab Luzon. However, I don't believe anybody ever in the US or Spain said "take Micronesia too" or instead of the Philippines. In fact the US paid significantly less than it should have for the Philippines. Perhaps if they had been willing to "bundle" they could have bought Micronesia as well by promising a more realistic amount of money (or to drop the requirement that Spain take Cuba's debt). Micronesia was useless and not realistically able to be governed by Spain without the Philippines, there were no other Spanish colonies in Asia, defensible ports or fortifications, or sizable population centers.
Keeping Micronesia allowed Spain to sell it to Germany the next year, 1899, for some much needed cash. Those islands were also good reason for Japan to enter WWI, what would Japan have gotten instead? Qingdao reverted to China, would Japan want it instead?