[PvK]

Burden of Time is only one of the Global Enchantments, many of which are very nasty. Not being able to dispel any Global Enchantments will always be a big liability IF you get into the high-level magic stage of play.

In a multi-player game, most Globals threaten everyone, and there will most likely be someone with enough astral competence to dispel.

In the special case of a single-player game where you don't want to get dispel ability and there is an enemy like Ashen Ermor that doesn't mind Burden of Time themselves, then yes it gives more urgency to dispelling it.

For a nation not like Ashen Ermor, though, BoT is going to hurt them as well. Nations basing their forces on undead have major weaknesses to cheap priests, who are easy to mass-produce and it doesn't matter if some of them die every turn. And, several other anti-undead techniques. There are plenty of things that are scarily powerful about death and unholy magic and Ashen Ermor etc., even without BoT. There are also many things that bLast them to dust, take them over, get them all to dissolve, etc.

PvK