You misunderstand what the "in excess of" is signifying. It's not an estimate of anything or a forecast or substitute for a NOTAM. It's an observation of fact - the fact that aircraft right now are experiencing delays in excess of XX minutes. Nothing more. You want it to be more, but it's not.
It's like a METAR or observation of windshear advised on the ATIS or *any* other observation - it may or may not affect your flight later but be prepared for it to.
It's nothing to do with preventing us using our judgement or experience - we just don't have the tools to do it at the centre.
At the console the only tool we have to tell us delays is MAESTRO - that gives an idea roughly 90 minutes ahead (that's 90 minutes including any actual delay). It's a tactical tool so only includes aircraft actually in the air and not those about to depart. 60 minutes from arrival we could tell you your current delay is 10 minutes but then 10 aircraft depart to arrive before you and your delay is now 40 minutes.