they are much more expensive and tend to depreciate in value
they can severely limit where you can get to and which camp grounds allow access
much harder to find a large enough camp site when campgrounds are nearly full
may not be able to get out of a campsite if another camper has left there vehicle unattended in the way of your hitching and towing out the caravan
more can go wrong - gas leaks, water leaks, towing issues, wheel issues, van brake failure due to failed connections, etc
unlike tent scenarios where worst case you just buy another tent, stove or fridge, if things go wrong with a van, they can be time consuming and expensive to fix - if you can fix them - parts or mechanics may not be easy to access - especially over holiday periods or in more remote areas
need a fairly large area of reasonably flat ground plus use of ramps under wheels to ensure relatively flat
many campgrounds now have bollards which prioritises tent campers and may make finding a caravan or trailer site difficult - especially if you want to set up a awning
generally need extra height access so camp grounds with low hanging trees can be problematic
high risk of accidents whilst being towed, including loss of control at speed, hitting pedestrians due to poor visibility, or poles when cornering due to poor judgement or visibility
they will require use of much more fuel to tow
some do take some time to set up and pack down
they can get very hot in summer time if there is no air conditioning - air conditioning will require a LOT of electricity and necessitate large batteries and solar panels
they can get very cold in winter unless you add extra heating such as a diesel heater but this can be noisy for other campers
some require considerable physical abilities to set up and pack down, and some require a 2nd person to assist
require storage when not in use
constant risk of them being stolen by being towed away by thieves when unattended
kitchen sink just dumps oily/detergent water with food/meat scraps straight onto the camp site attracting flies and wasps while contaminating the site for the next tent or swag camper - this is NOT Leave No Trace camping! Please put a bucket to catch it and dispose the waste appropriately.
they require the towing vehicle to be appropriately matched to the caravan weight loaded - a Toyota Prado will not cut it for a larger, heavier caravan!
they need to be optimally weight distributed for safe towing
you will most likely have to have it weighed to ensure it is not heavier than legal weights
if using a 24V system, you will need to have voltage converters to be compatible and if a component fails, it may be hard to find a 24V version in more remote areas while troubleshooting a 24V system is far more complex and dangerous than a 12V system (48V if even worse in this regard!)
it is likely you will need a special caravan towing licence at some point when govts bring this in to reduce caravan related road accidents