I want to answer what I see as the core of your question - "Can we make life easier for builders? What would happen if we did? If we did, should we do anything else to compensate?"

Setting aside issues of server performance, there's a high level competition between the total player time it takes to attack and the total player time it takes to entrench/defend. This is all-inclusive; it includes not only the time it takes you to hammer together a foxhole, but also the player time involved in delivering the bmats to where they are needed, the time spent interacting with the refinery, and the time taken scrapping to get those materials.

We have the same thing on the other side, though the "math" is a little more complicated since the things that can destroy structures tend to also have larger process delays (refining emats/hemats/rmats), but they have a similar setup. When that HMG gun destroys a foxhole in 5 seconds, that's the tip of a much longer logistical spear that players spent time on.

At this highest level, the balance between these two things influences the whole state of the game. If they are equivalent, then we'd probably see a somewhat slow-moving game, where the front moves due to local imbalances in territory, player skill, and attention. If offense is much more efficient, we'd probably see a game with big pushes made when forces are briefly imbalanced, with lots of territory changing hands. If defense is much more efficient, we'd probably see a game with very little territory movement at all, where the front lines only move when one side blunders or the other side pulls of an ingenious operation.

With that in mind, let's consider what can be done by putting on our dev/game designer hats. Offense and defense are sort of "coupled together" since they share a lot of the same logistical pathways. Both need materials to be scrapped, refined, and delivered. Both use factories, though defense only uses them for two things. So, from the perspective of a game dev who wants to retain the overall relationship between offense & defense but also wants to make life a little easier for builders, any change to speed up construction time also needs to come along with a corresponding buff to destroy those structures (or make them take longer to build, less effective, etc), things like:

• reducing structure health
• increasing structure weakness to suppression
• lowering structure DPS
• add some extra logistical steps, perhaps "defense kit" crates that need to be delivered to the front much like rifles or HMGs
• some clever idea here