if it was reduced to 15min, it would mean it can eventually be reduced to 1min30sec which is too low, also many servers would not like the change, and in singleplayer you can just use commands, and if u use them then to hack in items thats your choice
some people on older laptops or PCs either lag intensely or their laptop freezes for a short bit after fast travelling, meaning this would just downright kill them, making the mod almost unplayable for those with a worse laptop even if they were able to play it before
In my opinion the Isengard one is almost useless compared to other factions, since npcs pretty much never use explosions, and nor does pvp. However, pretty much all the other abilities are very useful in pvp or pve. I would suggest changing it to instead either increase damage dealt, or reduce damage taken.
i very much like this idea, it would add lots of building potential and make building easier