Simple reason is they wanted an epic crash scene. but if you want the technical reason then i dont think that escape pods have impulse engines. only thrusters. (perhaps some techy knows for sure?)
so the saucer is moving away at full impulse and still gets hit by the blast. escape pods will be moving at thrusters only, (maybe a lower impulse at max) and even with the increased time still would have been closer to the ship than the saucer was so they would have been incinerated by the explosion.
if it has been a random explosion, it probably would have been fine, but this was a warp core explosion and the power/range would have been too much for the pods to escape.
Riker was drunk during the end of the Enterprise. It's the only explaination for why he was such a bad commander in the moment. I mean seriously, why did he just not have worf open fire with everything the enterprise had? If you don't think to refrequency teh shields when they get penetrated (I can forgive this being overlooked cos they don't know how they did it, and if geordi did refrequency the shields, the duras would still be able to see and alter accordingly), then why not just open up with everything? I blame Worf for this just as much as Riker. One beam? Seriously? One beam against an ancient scrap pile that the people flying state is a scrap pile with no chance of going toe to toe? Sure, they probably would have got more shots in, but this is the Enterprise. Galaxy Class. It has serious firepower and should have used it.
Ramble got away from me.
Point is, Riker's entire commanding in those moments is questionable. But he didn't expect the saucer to crash is the real answer. He figured they would have time to get away, and the saucer has a much better chance of structurally surviving a core breach. Escape pods only have thrusters (way too small for impulse engines of any kind). Even if they had explosive jettison, they probably wouldn't have got away.
And maybe it was like the Titanic. Not enough life pods to go around?
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