When they show the 3DS on E3, they want to have positive reactions from the Nintendo fans.
Not angry reactions from fans, who just bought the DS XL a couple of months earlier.
Positive hype = priceless

From my view, best to reveal it now and keep people from buying the XL (which I don't think was going to do spectacular anyway), rather than get 10 million people to buy it and then piss them all off by revealing the 3DS shortly afterwards.

Besides, I think the DSXL serves a purpose that the 3DS won't quite fulfill. It allows older people with bigger hands and maybe worse vision to play it. Like the Gameboy Micro and original DS, I think XL and 3DS can coexist well, at least for a time, because they cover somewhat different markets.

No, Nintendo isn't stepping on any toes. Since DSiXL is for older or people with some sight imparement I suspect that the 3DS is something that won't be appealing for that market.

So are the analysts not understanding the Consumer market +1 more to the ever growing score.