If the instructions indicate getting power directly from the battery, then there might be a reason for it.
Only thing i can think of is the amperage required might exceed the fuse panel capability.
If thats the case, not saying it is for sure then it could be a fire hazard.
If you decide to run a power wire directly to the battery;
make sure you use a heavy enough gauge wire or the wire that came with the kit,
shield the wire with wire shields found at any auto parts store,
run the wire out of the way of any moving parts and hot spots that could melt the wire insulation and shield,
zip tie the wire so it is secure and doesn't flop around preferable along the firewall and fenders,
AND MOST IMPORTANT, place the inline fuse/holder as near the (+) battery post as possible and is clearly out of the way of the chassis, engine, etc.
Good Luck, done similar (not power locks) a bunch of times.
2014 Patriot Latitude 4X4 | 2000 Jeep XJ | 2016 Ford F150 XLT | 2005 Dodge Neon