Honestly, they embellish just like American athletes do. Basketball in particular has a lot of large men flopping around. You've got the attempts to get personal fouls in the NFL, and so on. Every sport has it, just seems like soccer gets the most guff for it because it's not an "American" sport.
As mentioned above, you can get carded for "simulation". Only really happens when it's obvious. Bear in mind there is 1 ref for the whole field, so it's not always seen.
Also, aside from the embellishment, a lot of these guys are running full speed while trying to keep their balance and control of a ball at their feet. One slight clip to the leg or ankle is gonna send you down. Think of a guard driving full speed through the lane and he steps on someone's foot. Even a slight change can impact balance in a big way.
There have been a lot of very good foul calls. I can say from experience that taking a cleat to the ankle is extremely painful. In fact, the worst sports injuries I've ever seen have been soccer injuries. Think Kevin Ware from years ago, but worse.
I dislike the teams that make it part of their game plan. The Portuguese and Uruguayans in particular tend to hit the ground when a calm breeze sweeps through the stadium. Most of the other fouls you see really are fouls.
For those that don't watch it much, I would liken it to my education in lacrosse. You don't realize how physical it really is until you see this level up close. I would say for those interested, the big European leagues start in August. NBCSN covers the English league and Fox covers the German league. Watch the best teams there and you may appreciate it more. Its like 90 minutes of motion offense and coordination.