No being close and flanking really isn't ok, using ranged attacks up close provokes OAs each time I do it, so doing it is suicide.
You can't flank at all with a ranged weapon so that's not what I meant. I was talking about stabbing the target with your dagger in melee (minor action to draw), for which you have +8 to attack (+10 with the combat advantage). If you use piercing strike, you target reflex which is typically 3 point lower than AC which gives you, I believe, the highest chances of hitting of the team. Just look at the monsters we are facing and see what +10 against reflex gives you. That's about 4 points better than when you throw a shuriken with combat advanatge in most case. If you target a guy that is already wounded, odds are good you kill him altogether and don't have to worry about his reply.
If you target in melee a guy that is marked (Which you always should when risking melee), the enemy gets -2 to attack you so your effective AC bumps up to 18, same as Tel, better than Aelek's and one short of Mal. Plus, if he attacks you, he takes 7hp of damage or an attack of opportunity, depending on whether he was marked by Tel or Mal. Often, he won't risk it, or gets killed trying it.
Plus, as I said, we have powers to help you. If you flank something with Mal and don't kill it, Mal can use covering strike next before the enemy attacks you. Worst case scenario, Mal misses and the target is marked. Best case scenario, you shift two free square away and he can't attack you at all.
Aelek aslo has a few trick up his sleeve, I expect.
I'm not saying it's your primary option, not at all. It is certainly more dangerous and a rogue built for melee would have things like toughness and hide armor to help himself that a ranged rogue doesn't have. But if cover is slim on the ground, it certainly can be a very good option when used judiciously. In fact, in certain situation it is tactically smarter to attack in melee than at range, despite being built for range. For example, If we really need to finish a powerful monster that we know is low on HP, should a flanking option be prsent it can be much better risking moving next to him and doing +10 piercing strike against (14 REF) than risking a stealth check and shooting a shuriken +9 (18 AC) if you suceed.
Deft strike is also top notch for that. Use the free two squares to close the gap, attack, shift away. If the target is makred by a fighter he can't follow you.
(Do you have deft strike or Riposte strike? I don't remember but I hope you have deft strike. It's even better for range than melee. Meanwhile riposte works only on melee and depends on strenght)
All I'm saying is that it's a powerful tool in your repertoire if used right. They designed the rogue in such a way that even if you focus on range, you always have solid melee options.