When our Founding Fathers crafted the Constitution of the U.S. (and later those who wrote Illinois' Constitution), they must not have envisioned elected officials spending most of their lives in office. They were farmers, merchants and of course lawyers who took time away from their careers to serve the public cause, then return to their normal lives again. It was necessary to have elected persons from every district and territory of each state because communication was poor and distances vast by horseback.
Today, communication is instant, travel is fast, and we know pretty much what is going on everywhere as it happens. The U.S. House of Representatives has about 435 members for 50 states. Illinois alone has 18 U.S. representatives, which is probably more than necessary in today's world.
In contrast, the Illinois General Assembly has 59 senators and 118 representatives. With partisan bickering, is it any wonder little gets done? A smaller state government with 15 to 20 politicians representing larger regions would make more sense, get more done, and cost a lot less. Term limits of six to eight years are also very important because they change a politician's main focus from "How am I going to get re-elected to protect my cushy job?" to "I know this is temporary, so what can I get done in the time I have here?"