Apple (NASDAQ:AAPL) is sticking to the same form factor of last year's iPhone for Friday's launch of the iPhone 5s and the iPhone 5c, but the same can't be said about the competition.

BlackBerry (NASDAQ:BBRY) is going to go with a 5-inch screen for the new Z30 smartphone, a nice bump from the 4.2-inch display of the Z10 device that has languished since being introduced earlier this year.

"The new Z30 brings BlackBerry 10 to the big screen for a richer, more powerful experience," begins the promotional video that rolled out this morning. 

Nokia (NYSE:NOK) tweeted yesterday that it will show why it never stops innovating on Oct. 22. The Verge is reporting that the Finnish handset maker will be introducing a Lumia device with a 6-inch display.

Naysayers will argue that BlackBerry and Nokia are nuts. They are trying to disrupt any momentum that Apple may gain during this week's launch by pointing out how their devices are bigger, but these are fledgling platforms; BlackBerry and Windows Phone command less than 5% of the market apiece.

However, it's not a coincidence that BlackBerry is playing up the larger size of its Z30, a device that's just being announced today but may be available in some overseas markets as early as next week.

They know that size is Apple's shortfall. For inexplicable reasons, Apple has been reluctant to join the more popular Android devices that are available in 5-inch screens or larger. Apple has chosen to stick to its knitting, even if it translates into global smartphone market share declining over the past year from 17% to 13%.

Apple's counter has been that size isn't all that matters. Retina display, dude! However, fingers don't get smaller.

It's pretty telling that Apple is offering the 5c in five different colors and upping the current generation's choices to three metallic hues, but it won't offer consumers a choice in screen sizes for the iPhone. Does Apple know that colors mean little in a world where many turn to protective cases? These aren't tiny iPods, you know.

We may never know how much market share Apple is surrendering by refusing to offer the big screens that Samsung, HTC, and now BlackBerry -- and possibly Nokia -- have been gravitating to with their latest smartphones. History only offers us one path. However, ignoring the larger smartphone screens and phablets that have turned Samsung into the global leader has to be seen as a failure.

Apple has some growing up to do -- in more ways than one.

Longtime Fool contributor Rick Munarriz has no position in any stocks mentioned. The Motley Fool recommends Apple. The Motley Fool owns shares of Apple. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.