At single runway airports, where you are at max. capacity, conditional clearances can provide a great deal of situational awareness.
As an example, if you have very tight departure gaps in a constant stream of landing traffic you might use the phrase "Behind the landing XXXX, line up and be ready immediate". This immediately implies that a degree of urgency is required on lining up and I would like to think that the aircrew then look out of the cockpit, see the stream of landings and make a quick assessment of whether they can complete their take-off checks in time. At the same time it gives a verbal heads-up to the first landing aircraft that they should not delay their exit from the runway. Finally, it gives the following landing aircraft an indication that there will be an aircraft departing before them and implies that they will probably receive a late landing clearance. It also indicates to anyone else on frequency that this is a busy airport trying to shift as much traffic as can safely be done.
Suspension of conditional clearances sounds like a knee-jerk reaction to a one-off incident where the full implications of not using them haven't been thought through properly.