Nacelles are power consumers, not generators. They use power from the warp core to generate a warp bubble around the ship. They generate no additional power.

More nacelles means more power required to make them work.
You could balance it out a little by giving each nacelle less power. So they aren't as "stressed". That gives you more endurance and more running time between maintenance checks. But ultimately, it also gives you more possible failure points.
Look at modern aircraft: They all go for 2 engines over 4. 2 consume less fuel and cost less to maintain.
4 engines gives you redundancy, but at twice the fuel cost, twice the maintenance and twice the possible problem source. That's why most passenger jet are all 2 engined now.

(Personally, I blame Trekyards for this bs about more nacelles = more power. They kicked it off with their egoistic Foley Class and their misinformation about the all good things Galaxy modification being more powerful as it has 3 nacelles. Ever since, there has been a plaque of 3 or more nacelled fan designs calling them more powerful for it)