I ride clipless, though I normally use
pedals that allow me to ride comfortably in uncleated shoes if I want to. Shoes with recessed cleats (usually sold as "mountain" something) are pretty OK to walk in anyway; just watch out for slipping on cobbles, and don't walk on polished wooden floors in them. Although all clipless systems take a
little getting used to, the modern SPD-style (if properly adjusted, kept clean, and lubed) make it pretty easy to release a foot in an emergency.
Stick with the drops for a bit. Cyclocross bikes generally have wider bars and you may well find them more versatile than flat bars. It's not like you'll lose out.
Or consider touring or "randonneur" style drops (less drop), or "moustache" bars (much less drop). Flat handlebars can be good, but it depends what you mean by "flat". The typical straight "mountain bike" style bar that bike-shops tend to fit is not a good idea for road riding IMHO. They force your arms into a rather unnatural "elbows out" position that can become seriously uncomfortable after a few hours of riding. People fit bar-ends and other extras to alleviate the problem, but I don't think they're a good idea for riding in urban traffic, because you can't cover the brakes from a bar-end riding position. A better option is one of the M-shaped handlebars that used to be typical of traditional utility bicycles. These are sold under various names, including "North Road", "Town", and "Sweep". They're the same tube diameter as standard straight bars, so fully compatible with brakes, shifters etc.
Which brings me to a final point. Bicycle parts are subject to many annoying historical standards and incompatibilities, and handlebars are no exception. Drop handlebars are typically made of different diameter tubing from flat bars, and swapping from one to the other can mean that your stem, brake-levers, and gear-shifters will not fit, so you can indeed "lose out". Some types of brake-lever are incompatible with some types of brake mechanism. Some gear systems come with shifters that will only fit one diameter of bar, or will only fit on straight sections of tubing, and this can constrain your other choices. Going from drop bars to straight is usually easier than the other way round, but fiddling around with handlebars can become a frustrating pass-time. Do not ask how I know this...
There's a good article on handlebar choices
here.
Edit: Rereading the above, I realise that I am a huge bicycle nerd.