Microsoft has taken initiative to say bye bye to IE6, the reason is very simple and understandable. IE6 came in the market 10 years ago when web was evolving. Now, in this era where web has improved in leaps and bounds in last 10 years. We need a browser which is fast and beautiful which is none other than IE9. It is true that  IE9 can be installed only on Windows 7. If one has some other version of Windows I would sugggest to upgrade to IE8 and get rid of IE6. Below image shows the usage of IE6 world wide.

A web developer spends significant amount of time to support IE6. Below list shows why you should IE9 or atleast IE8.

Performance	Internet Explorer 6	Internet Explorer 7	Internet Explorer 8	Internet Explorer 9
Fast startup and shutdown	–	–	–
Popular websites load quickly	–	–
Fully hardware-accelerated HTML5 for tomorrow’s rich web experiences	–	–	–
Competitive on popular JavaScript performance micro-benchmarks like WebKit SunSpider	–	–	–
JavaScript engine that both interprets and compiles code for better	–	–	–
JavaScript compiled in the background on secondary core	–	–	–
View and manage add-on performance	–	–
Automatic notification of add-ons that slow down browser performance	–	–	–

Security and Privacy	Internet Explorer 6	Internet Explorer 7	Internet Explorer 8	Internet Explorer 9
Pop-up blocker
Protection from phishing attacks	–
Protection from socially engineered malware	–	–
Sandboxed mode to limit impact of rogue add-ins (Windows Vista and later)	–
Support for DEP/NX	–	–
Delete browsing history (with granular control over cookies, passwords, and so on)	–
Privacy mode to browse without leaving any data on the PC	–	–
Highlight domain names in the address bar to help alert you to deceptive websites	–	–

Interoperability, Standards Support, and Compatibility	Internet Explorer 6	Internet Explorer 7	Internet Explorer 8	Internet Explorer 9
Quirks mode for very old websites
Support for standards commonly used today (HTML 4.01, CSS 2.1)	–
Support for next generation standards like HTML5, CSS3, and ECMAScript 5	–	–
Compatibility mode for older sites	–	–
Comprehensive developer tools built into the browser	–	–

Reliability	Internet Explorer 6	Internet Explorer 7	Internet Explorer 8	Internet Explorer 9
Tabs isolated into separate processes to limit the impact system failure (crash)	–	–
Automatic recovery of tabs that have stopped responding	–	–
Tab recovery for when websites time out	–	–	–

User Experience	Internet Explorer 6	Internet Explorer 7	Internet Explorer 8	Internet Explorer 9
Simplified browsing experience with fewer controls and increased web page viewing area	–	–	–
Site-centric user experience that puts the focus on your sites	–	–	–
Rich tab functionality (color coding, grouping, tear off tabs, Aero Snap)	–	–
New tab page includes common tasks and your favorite sites	–	–
Rich address bar (suggest sites from favorites and history, visual results)	–	–
Combined search and address bar that enables the user to send text to search providers as you type	–	–	–
Easily change search provider from Search box	–
Quick access to common services like mapping	–	–
Support for site pinning in Windows 7	–	–	–
Support for jump lists and thumbnail preview for the browser on Windows 7	–	–
Non-intrusive notifications	–	–	–
Download manager	–	–	–
Spell Checker	–	With Add-ons	With Add-ons	With Add-ons
Sync favorites, themes and settings	–	With Add-ons	With Add-ons	With Add-ons
Reopen accidentally closed tabs	–	–

Above comparision is from ie6countdown

Let's join hand together and make this happen.