Let's break this down into the three questions that it actually entails.
1) If consoles are just very restricted computers why don't all console games get a PC port?
In the loosest sense, consoles are PCs. They have the same basic hardware (CPU, GPU, RAM, ROM, etc..). The big difference is that consoles run both different instruction sets, and have different structures.
It's possible to take a language written on a PC, that won't run on it, and send it onto a console that can actually understand the language and run it. This is why developer consoles exist, and the console isn't just emulated on a PC. Rewriting the language to a different one is a time consuming task, as some features that are easily used on a console might not be there on a PC, and vice-versa.
PowerPC architecture, a common component of older consoles, isn't x86. If the CPU is structured differently it doesn't matter that all of the components are the same otherwise. It's a lot like language. English stole a lot from German, and some words are an exact duplicate of one another. This doesn't mean an English speaker can converse with a German speaker.
2) Why aren't there many PC games from Square Enix?
Seriously? Have you seen their online store? It's arranged in the most bass-ackwards fashion possible, but just look around a bit
http://store.na.square-enix.com/store/sqenixus/en_US/list/ThemeID.29853700/categoryID.57606100/size.46/startIndex.0/. Square Enix has tons of PC games. They don't promote them well, they support them worse, but they do have them. The FF7 ultimate edition from the 90's still worked on my XP x64 system (boy, did it take a lot of work to get it running though). On the other hand, Deus Ex and Supreme Commander. Enough said.
3) Why aren't there any JRPGs coming out?
There are three reasons. The JRPG lost itself, tools were developed to pump out low budget releases, and the gaming target market doesn't have the time investment available for a JRPG any more.
In the 8 bit days the JRPG ruled the world. They were developed in the one country that loved them to death, and they were the only way to get a huge story onto a piece of silicon (text was king here). As the gaming industry grew, so too did the storage capacity and tools for the medium. Most games moved from having no plot, into having a story. Racing games got drivers, shooters got distinct heros, and games developed to where a cohesive narrative was possible. The JRPG did not respond to this, it just used the extra room to make bigger battles, bigger worlds, and prettier graphics. As the years passed, the JRPG decided to catch up to the times by introducing quick time events, moody "mature" characters, and grind. This method ignored a complex and engaging narrative, which is where the JRPG lost what made itself special.
RPG maker, a Japanese tool if I remember correctly, proved that the formula for a JRPG had become stagnant. A decent coder could set up a game akin to FF6 or lower in a month. That kind of depressingly easy curve has led to larger companies deciding that the JRPG market isn't profitable. A thousand JRPGs cranked out by a hundred companies over-saturates a market, to the point where nobody wants to buy the latest release. It isn't pretty, but developers are to blame for this practice killing the market.
Let's spend just a moment looking at what a time investment that a JRPG is. Assume the average 20+ year old has about 3 hours an evening to play games (1 hour for people working, 5 hours for college/unemployed). This means an average week is about 15 hours of gaming. Let's also assume that the average JRPG requires about 75 hours to complete. You're looking at a five week investment. For the very busy, an entire year or more. I've never been able to tell what I ate for dinner 2 weeks ago, let alone a minor plot point from a game that I played five weeks ago. As the target demographic for video games relocates, so too does the available time. Fast paced, bite-sized, experiences sell better. The latest FF games, versus the latest CoD games, are accurate proof.
So I think the question you really wanted to ask was "How do we get more JRPGs to get onto the PC?" There's a simple way, buy them. Steam has a plethora of these games. Cthulu Saves the World is 100% pure awesome JRPG. Go out and buy that game. Additionally, write Square Enix. A letter saying that you will not purchase another FF13 spin-off would be great. Perhaps suggest that you don't want an MMO, a shooter, or a linear battler. Writing to these companies seems archaic, but considering the lack of QA on FF13, the written word may matter. If you don't like FF, then write to them about one of the other dozen JRPGs they've got. I'd personally love to see a new Chrono game.
Another note, support what the JRPG has become. Monster Hunter is a very good riff on the old tropes, without losing itself to slavish reproduction. Dragon Quest is another great modern JRPG. Tell these companies, with your dollars, that good quality JRPGs will see financial success. Also, don't buy remakes. FF7 was great, because we had nothing to compare it to. Playing it again a decade later was...unfullfilling. Poor character design, terrible dialogue, and a broken pacing system do not a great game make. When the emulated FF9 is miles better than the PC native 7, you've got to put your foot down.