The main differences between HDL vs schematic entry are abstraction, portability, and maintenance.

HDLs allow a much greater level of abstraction than a design entered schematically. The downside is that you have less control over how the design is actually implemented and the performance can suffer. Sort of like the assembler versus C/C++ debate. However, modern synthesizers are so good that this is largely irrelevant. Designs entered schematically suffer greatly from not being portable or easily modifiable. HDL descriptions provide technology-independent documentation of a design and its functionality. HDLs also give you much more flexibility when it comes to parameterizing your design. HDLs also don't require a propietary viewer to browse the design. Lastly, large designs are easier to handle with HDL tools than schematic tools

Of course you can always mix and match design styles. I usually do the majority in HDL but make the top level a schematic.



Such tools do exist but the quality varies greatly. You can usually generate both an RTL and a technology schematic from a synthesized HDL netlist. The quality of said view depends on the synthesis tool you use.