i agree but... not many people here have a connection that allows 200Mbps (let alone 1Gbps) to start with. for solo traders 54Mbps with 90% minimum signal strenght is more than enough - your adsl provider will likely not support more than 16Mbps (in/out). speed difference is in double digit miliseconds delay for WiFi so - again - for majority people here that does not matter. but for 16 traders i agree it is a different matter.
also, you have to think about how the bandwidth will be shared between all 16 computers. latency will start to be an issue with 16 computers and wifi as well. the solution is this: do not use wireless. any network admin could inform you that using wireless for your application would be a terrible idea.
I agree that sharing the wifi bandwidth on the same access point by 16 computers all running trading applications that require streaming data (and imagine if they all have multiple monitors and lots of charts) is very questionable. Plus the added security concern. Also the signal strength (therefore bandwidth) is unevenly distributed depending on how far the computer is from the AP. I travel and trade sometimes. Most of the hotels now offer only wifi access and no landline RJ45 connection. Experience at one hotel in San Diego, my Internet access speed went to a crawl at 06:30 am. Turned out my next door hotel guest was running some downloading program all night long for gigabytes of files and he ate up most of the wifi bandwidth and left me with scraps.