Who makes

Is the current output more important than the voltage as that is what gives the speaker its dynamic range? What is voltage good for? It seems like a cheap way make the amp appear to be powerful when reading the specs.

voltage & current are duals of each other - where you will find voltage, you'll find current flow. The converse is also true - Where you'll find current, you'll find voltage. Voltage & current cannot exist without each other.
Think of voltage as electric pressure (old engineering texts had voltage as E) similar to water pressure. Current flows from higher electric pressure to lower electric pressure.
When an amp is delivering power into a speaker it's a combination of voltage & current. The voltage impressed (by the amp) at the speaker terminals causes current to flow in the passive x-over components. Depending on the various values of R, C, L in the x-over components, these respective components develop a voltage across them proportional to the music signal. This gets xferred to the speaker drivers. It's the voltage signal that causes pistonic movement in the speaker drivers & that produces sound. No voltage, no sound. So, voltage is good for a whole lot of things. How much current can be output from the power amp depends on how robust its power supply is. So, as Mapman suggested, not all watts are created equal in the sense that 2 100W amps might have vastly different power supplies. in such a case, the power amp with a more robust power supply will be able to drive a more difficult speaker load because it will be able to output more current into the difficult load to create a proportional-to-music-signal voltage for the speaker drivers.
Amps with a weaker power supply cannot drive difficult loads (yet it will still be a 100W/ch amp).

Thanks Bombaywalla,
This also explains why certain amplifiers rated at say for example 40 watts/channel can out drive another amp that's rated at 100 watt/channel . Power supply quality matters.

YEs, and most modern high quality speakers that are not large and use porting and other methods to deliver extended low end bass response out of a smaller package, as is popular with most these days, ARE difficult loads, even quality small monitor style speakers with top notch low end extension for their size.

COmbine that with a lot of the popular and low cost commercial amplification devices out there that also tend to emphasize many features in a small package that most can handle easily that use relatively small and inexpensive power supplies to deliver their watts as well and you have 90% of the reason why so many systems you hear normally have such mediocre sound, even if the speakers are in fact capable of much more.

Its like connecting a fire hose to a house spigot and expecting to be able to put out a house fire as well as the one hooked up to the high pressure (voltage), high volume (current) fire hydrant down the street.

Yes, you are correct, Bob. Here we are talking about power amps & power amps driving speakers so in both cases there is an electrical circuit completed around the voltage source (the amp) which will cause current flow.
I assumed this due to nature of the question from the OP.