The purpose we want a PC that matches the performance of the console is :
1. It is a PC, anything can be done with it including Web Browsing, Media Steaming, Office Work, Productivity work and an endless list of things to do.
2. There might be 5-10 games that are exclusive to the consoles but there are 1000+ games that are exclusive to the PC's including new releases and older games. There are way more than that. Most of the Indie games are just on PC. And Indie games are some of the most artistic games. Half Life, Half Life 2, and seriously many good games are PC exclusive.
3. Deals on Steam : There are always deals going on steam. Many times you can find AAA games for just like 5 bucks on Holiday, Weekend or in general any random sales. You can buy bundles from sites like Humble Bundle for like just 5 bucks for like 6-7 games. Also there are a lot more deals available on PC's in general which are not there on consoles.
4. You would need to pay $50 for an yearly membership with the Xbox or PS4. But with PC for the same money you can get like a lot games for $50 if you can look for deals. You would have to pay a lot less.
5. There are older games that would never come to consoles. You cannot play GTA VC on consoles. You cannot play Super Mario Bros on consoles. You cannot play IGI on consoles. You cannot play GTA SA on this gen consoles. You cannot play CS 1.6 on consoles. In other words you cannot play any older games with consoles that you might have loved from the past.
6. Playing FPS games with the controller sucks. Seriously it takes out the fun of having the skill to aim and shoot. With console everything is Auto Aim. Seriously that is no fun to play.
7. You can mod games on PC. Elder Scrolls Skyrim and GTA series are great examples. Especially on Skyrim you can put on High Res texture packs, everything high resolution packs and enjoy the looks and added features the mods gives. You can change the cars, looks of buildings and transform the game to every imaginable way you prefer to with the PC. You cannot do the same on consoles. There are always phrases thrown like "My Skyrim looks better than your skyrim" . That phrase is self explanatory.
Also Counter Strike and Team Fortress first started as mods and then became awesome games that everyone still loves
And seriously, the possibilities are endless with PC's on gaming, entertainment and productivity front. And you have the freedom to choose what you want to, unlike what the console manufacturers want you to use and pay for.
There are a tonne more reasons to move from console to PC's. You might want to refer to this Video by Logan from TekSyndiate (razethew0rld). Some points above are taken directly from that Video linked below.
Kill Your Console - Reasons to Switch to PC (http://www.youtube.com/watch?v=TUhdL-ITG-M) - TekSyndiate
In simple words, with PC you are free but with consoles you are tied to the manufacturer for the rest of your life, unless you plan to throw the console and not use it at all.
This is why I would recommend a PC to anyone over a console. Watch the Video, you will learn more.
I hope this piece of information helps.