There are plenty of reasonable reasons not to use CCA wire.
It's chief advantage is it is cheaper and lighter than copper based wire.
Because of the reduced current carrying capacity of aluminum, add about 3~4 AWG to the equivalent copper cable. So you are in effect using AWG 17~18 copper-equivalent speaker cable.
Although the skin effect is certainly operative, at audio frequencies it isn't significant, so little to none of the current going from your amp to speakers is along the copper layer; you are basically using aluminum cables.
The copper layer is simply there to overcome the corrosion effect of bare aluminum; which oxidizes almost immediately in contact with air. Aluminum oxide is a very poor conductor ... much worse than aluminum metal itself ... so any area nicked on the cable where bare aluminum is visible will essentially not conduct.
Unless you are using gas-tight connectors (and HiFi amp/speaker binding posts generally are not) you can expect the cables to deteriorate over time with regard to electrical transmission.
Regular application of environmental metal cleaners is highly recommended. A bottle or spray, wipes or pen of Deoxit is highly recommended, along with regular cleaning/application.
To sum up, I feel there are plenty of reasons not to use CCA wire in a HiFi application. There is no need to go into sonic characteristics, but for what it's worth, to my ears CCA sounds terrible (brittle and lack of dynamics). Others may disagree, but essentially it's moot. They are a poor choice without subjective assessment being brought into the argument.
The wire you purchased is generally used to build radio antennae, where the aluminum layer's light weight is an advantage and where the high radio frequency is able to use the skin effect to carry the signal on the copper layer.
It's not completely relevant, but for a time in the 1960's homes were built with aluminum AC wiring. Two issues developed, somewhat related. The corrosion of the aluminum cable made poor contact with brass and copper AC connectors used elsewhere (AC outlets, marrettes, breakers, etc), causing sparks and eventually home fires.
Aluminum is also brittle, and will not survive many, or even a very few, bend cycles (in sharp contrast to copper, which is amongst the most bendable metals in existence). Cracks tend to develop where connection is made. Again, breakage of the aluminum wire in homes caused fires. The use of aluminum AC wiring is currently banned in Canada and the US.
In the end, you would be much better off simply by using good-old-copper cables. AWG 18 lamp cord is available for a similar price to your 14 AWG CCA cables, if cost is your primary consideration.
