For complex designs the simulator that comes with the Vivado tools (Mentor's modelsim) is not going to cut it. I wonder if they are working on deals with Mentor (or competitors Cadence and Synopsys) to license their full-featured simulators. Even better, maybe Amazon (and others getting into this space like Intel and Microsoft) will put their weight behind an open source VHDL/Verilog simulator. A few exist but they a…
As someone who has little experience with FPGAs beyond some experiments with a Spartan-6 dev board that mostly involved learning to write VHDL and building a minimal CPU, I found the simulator to be of limited use. My tiny projects were small enough that the education simulator was plenty fast. It was nice when I didn't have the board available, and occasionally, the logic analyzer was useful when I didn't understand…
That being said, you are far from alone as an FPGA developer in skipping sim and going straight to hardware. Tools like Xilinx's chipscope help with the visibility problem in real hardware too.