I've only purchased wifi version of tablets and have gotten by fine. It's not really a matter of it being problematic, it's a matter of having internet connectivity or not. If you plan to use the tablet only in places where there is a wifi hotspot nearby then you should be fine. However, if you plan to use the tablet where there are no wifi hotspots then you'll be able to connect via the cellular signal (provided there's a cell tower nearby).
With the wifi version, you can connect to free hotspots and use it without additional cost. With the 4G connection version you will need to pay an additional monthly cellular charge (you'll pay that charge regardless of whether you actually use it or not).
If you have a cell phone, you may be able to share its cellular connection with your tablet by creating a hotspot on your phone. That's what I do so, IMO, there is no good reason to ever buy a 4G enabled tablet.
