Why would you get rid of FTL when several solutions have been given to make it work. Is there seriously a reason to completely switch when one can make what they know work?

All methods of leading have their advantages and disadvantages, FTL is long lead time, with greatest overall flexibility, and seamless transition between chars.
Focus is simple and hardware boxing compatible, but gives up the hidden nuke target / CC fallback ability of the focus frame, and requires memorizing a key for a particular char to become lead.
Party--whatever is about useless if you ever plan on doing something with raiding or PvP in mind.

I would read the OP's question and try to answer it using the method they asked about, if it's impossible state that, not your opinion on others methods. At the very least when presenting another idea support it and give us some insight as to why you believe it is superior and should be used.