I know the game reason for this mismatch of beam banks being more powerful than beam arrays, but in Trek canon the beam banks wer 23rd Century technology and beam arrays are 24th Century technology. With that in mind, shouldn't the arrays be more powerful than beam arrays. Let us take two ships similar in size, Constituion Refit and Intrepid. By game logic, the Constitution has more powerful phasers than the Intrepid. How can this be since the array is an off shoot of the beam weapon. The array represents an improvement in energy transfer in both intensity and versitality. Its like comparing a 5 in Naval gun of WW2 with the more modern, auto-loading, and rapid fire 5 in gun on today's Naval ships. The basic caliber may be the same, but advancements in technology made it more lethal. Therefore, the phaser array should be able to expel a more powerful energy wave than a beam weapon.
How would the game reflect this without changing the current settings in output? The array should have a faster recharge and better accuracy, so over time the phaser array can do more damage. The bank still has the short term advantage, but its main disadvantage would be a limited arc and slightly longer cooldown after muttiple shots. Again, I know the game make banks more powerful and less flexible (i.e. little to no overlap), but the array should be the high end of phaser tech.
The beam banks are "dual" beam banks--so they fire two beams compared to the Beam Array's single beam. However, they do only 130-140% of the damage of the Beam Array. This implies that each beam from the Dual Beam Bank is only about two-thirds as powerful as the beam from the Beam Array.
Also, despite the particular fixture design being older, the internals aren't the same. In DS9, the Lakota still had the two-ball style phaser placements on its hull, but had been upgraded with advanced phasers, quantum torpedoes, and other 24th Century equipment that made it a fitting tool of choice for an admiral who had numerous later designs at his call.
In fact, the OP's analogy applies better to that than comparing banks to arrays.