As far as machines go, the TE ones are more expensive across the board compared to IC2's, even in terms of energy cost, and even then - the only real valid comparison points are the Furnace/Pulverizer, any similarity begins and ends there.
With regards to the accumulator, it only pumps water, and the cost (in EMC) isn't far off from a BC pump + 4x RS engines. The only real difference is that it's a low latency solution that doesn't fail due to vanilla block update bugs. Given lava as a power source, the pump is a far more useful block in general.
It's not a question of making things better or easier - that would be trivial. It's simply a matter of making things work like the player expects them to work. You have liquid at point A and want it at point B? You run a liquiduct or a tesseract. There's no reason for that to lag the server, and there's also no reason for that process to be very difficult or punishing.
If I were shooting for popularity, yeah, I could lower energy costs or make things less onerous to make. When the REC came out, a large number of people were complaining about the steps required to craft one. Same with the conduits. I've obviously stuck to those recipes, however.
So, I'm sorry if you don't agree with TE's idea of balance, but the vast majority of people actually do, and it's not because they feel that TE is super easy. I mod for me; there have only been a couple of occasions where I have changed something due to external factors, and it's basically been rebalances to not screw Forestry or RailCraft. I think it's easy to point at TE and say that it's popular because it's not ball-crushingly cruel or obtuse, but I could jack the resource cost on everything (which, see the optional configs for this), and I bet it'd still get used lots, since it works.