You can't really compare Wilshire and Walcott. They play in different positions, have different attributes, and are of different stages in their development. Wilshire can't play on the right flank or as a supporting striker, just as Walcott can't play in left midfield.
Unless Wenger plays Wilshire ahead of Denilson or Diaby this season then he will benefit by being loaned out again. Walcott doesn't need to be loaned out - he can gain a whole lot more experience by playing on a regular basis for Arsenal.
In regards to the Barnet vs. Arsenal game - I only caught the last 15mins but from what I saw it was a very one sided game.
Ok, firstly Wilshire does play right wing, and suppor striker, and left wing, and Theo has most certainly played on the left for Arsenal, so thats all really completely wrong. As for Theo, he's gained entirely nothing by playing regularly for Arsenal, the only thing Arsenal gain by playing him, is taking up a spot a MUCH better player(we have numerous significantly better than him) could be using.
Its bad for Arsenal when Theo players, because he's the worst of many many options, he WOULD benefit by going out on loan, because he's walking around giving interviews about how he was shocked to not be in the England squad, how he thinks this that and the other. He needs a wake up call, which would be being told to smeg off, improve or end up leaving Arsenal for a low prem league, or even a championship club.
Likewise, Wilshire is significantly better than Diaby, and Denilson(whose been playing as a DM for two years), and should indeed start ahead of both of those. Wilshire is already better than a bunch of the idiots Wenger insists on starting, players who routinely end up being the cause of losing games.
Yes the Barnet game was one sided, Barnet have been crap, forever, we often thrash them 7/8-0, even playing lots and lots of our youth players, and this was the worst Barnet team for years, quite literally , they almost ended up non league last season. Frankly we should have done better, the team in the second half looked inept compared to previous seasons.
For the record, most of Wilshires appearances in an Arsenal shirt, be it friendly, cup, league, have been on the right wing, occasionally the left wing, he was mostly a right winger for the past 4-5 years.
He was also brilliant in last years preseason, but barely got a look in before being loaned out, he showed he was a far better play than many of those who we played first team throughout the season. Its madness to loan him out, and let him play with worse players, he'll learn more, more quickly and be a better player if he plays in the Arsenal team rather than say the Bolton team.