They were neutered back in the day because one of the Devs felt like they gave too much power and that it was way too easy to have high power levels.
Look at what we've got now.
Plasmonic Leech can give you +15-20.
MACO shields can give you +10 (or is it more?)
Warp Cores give you a bunch as well, let's say +15 to call it even.
That's +40 power without having to actually do anything - no BOff powers, no DOffs, no active player actions. Nothing. All it costs is 1 console slot (since you're have to run shields and a warp core anyways).
These consoles used to grant +7 to a single subsystem and that was enough to get them nerfed. Leech alone can give you +15 to EVERYTHING.
Why bother ever running an Engineering console that will give you +3.5 to a single subsystem?
Star Trek Online: Where the Developers would rather have you pay for the same ship over and over again instead of addressing (by their own admission) heavy power creep and the real underlying issues, despite their assurances to do so.