It doesn't look like a "massive" expansion in terms of gates. Looks like about the same number. Seems like more of an expansion in terms of space for security checkpoint and more variety of shops and restaurants by moving the Sky Club upstairs. Parking is probably the one thing that airports should not be adding anyway based on the rise of ride-sharing services..
While it is not a massive expansion of gates (they still did add some in the new concourse of Terminal 1 and 4), the expansion will allow them to expand the overall number of flights, specifically international flights. A big part of what they are doing is increasing the capacity of customs and immigration for the terminals serving international flights. The Terminal 2 expansion for Delta and the SkyClub is just modernization, and very necessary modernization at that, but the rest really is trying to make FLL a more appealing destination for international flights.
They've added a DXB direct flight on Emirates and a LGW direct on BA, in addition to the plentiful Latin America/Caribbean destinations. FLL is a very attractive destination for European, Russian and Middle Eastern travelers so I think the demand is there, who really wants to fly in and out of MIA if it can be avoided? Will it happen? I don't know, but right now FLL just lacks the infrastructure to do what they want to do, so I'm all for it. The actual logistics of it (gates, runways, etc) is not a problem.
As for parking, while I'd generally agree with you, FLL has a weird parking situation. Two of the three garages, the two nearest terminals 2, 3 and 4, are relatively small and often at max capacity while the largest garage is nearest terminal 1 and requires either a shuttle or an often times hot and humid outside walk to reach the other 3 terminals. That isn't to say it is awful, I'd still gladly take that over many other airport parking situations, but if you're in and out of FLL a few times a week it can be a grind and can sometimes add 15-20 minutes on either end of your flight. I really shouldn't complain though, it could be way worse.