In my experience Ryanair don't worry too much about hand baggage on departures from the UK but are obsessive about both hold and hand baggage on flights into the UK.
I can't comment on the situation with Ryanair checked bags (I only travel FR on their promotional fares, use a visa electron and take handluggage only (I like to think Ryanair pay ME to fly with them!!)) but as a general observation, they are getting much stricter than they used to be with handluggage everywhere, including the UK. They almost always seem to check baggage dimentions and strictly enforce the 'one bag' per passenger rule, limiting the amount of duty/tax free purchases passengers can make (especially if your bag is already bulging!). I've always wondered what the airports make of this, perticularly the smaller, cash strapped ones for whom duty free sales are an important stream of auxiliary revenue (someting Ryanair should be familiar with!).
This is not unique to Ryanair though. In short, I'd say that all airlines, including the full service carriers, are getting much stricter with regards to baggage allowances. As usual, for better or for worse, Ryanair are leading the way- a look at them is a good indication of what will be industry standard practice in a few years time. A wink and a smile got me onto an Air Asia flight 12kg over the checked baggage limit a few years ago. These days groundstaff don't have the discretion that to allow that to happen, even if they want to. Even Qatar Airways, whom I consider excellent in terms of customer service, always strictly enforce the 7kg limit on hand baggage.
If you don't want to fall foul of the rules, don't go over the limits!