Cool and thanks. Will you always add quick updates like this if something is broken and you can add a quick fix? If so then I will definitely stick with this OS.
When something is broken we'll obviously fix the source code as soon as possible, however whether that triggers a binary release depends on the severity of the problem, and whether there's any workarounds/temporary fixes.
In this case we're about to produce another Alpha before heading into Beta, so it makes sense to get this in ASAP. However once we've got official releases out, not every bug fix will result in an immediate release (unless we're doing a spectacularly bad job at testing!) as we will instead batch fixes for the next patch release, the frequency of which will be determined by the size of the fix list/severity of the bugs etc., but you shouldn't be kept waiting too long.
In the meantime if you run the following commands on your 6.90.004 system you should find you have working Bluetooth (if not, please post again):
mount -o remount,rw /flash
(cd /flash && wget -q http://milhouse.libreelec.tv/other/firmware_bt_fix.tar.gz -O - | tar xvzf -)
sync && mount -o remount,ro /flash
reboot
After running the above commands, you should have March 24 firmware:
LibreELEC:~ # vcgencmd version
Mar 24 2016 12:49:34
Copyright (c) 2012 Broadcom
version e16cd015026a8bda22bb50dc30b30ce07f52a202 (clean) (release)