The "legacy ThinkPad weirdness" is one of the reasons why ThinkPads are popular for Linux (and free OS's in general). Older ThinkPads were IBM PC first and laptop second, thus were designed such that the whole thing works reasonably well when you run DOS on it (ie. OS that predates ACPI and thus has no idea that such thing even exists) and it not only worked, but was actually supported by IBM. This allowed Linux to work reasonably without any special considerations towards laptop-specific hardware. Somehow, this was deemed insufficient and commmunity had reverse engineered almost complete BIOS and embedded controller APIs for ThinkPad line (it certainly helps that these APIs are remarkably backward compatible, even though IBM->Lenovo transition had broken some important features like hardware volume control)