Yes.
When the iPad 1st launched, and before I saw one for real, I saw in being demo'd on the internet, think they were using small women/Chinese/midgets or something, as in their hands the iPad looked quite large.
I ordered one, and as soon as I unpacked it (my large hands) I was like, OMG, it's much smaller than I though
I'd happy have a tablet a few more inches in size, 14" at least.
Without ANY Question, If Apple did make say the 10" and say a 12" or 13" model then many, and I mean many millions of buyers would opt for the larger model.
I'm not sure of the percentages, but I'd guess the larger model would be very popular.
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Absolutely not. The actual size is just perfect.
Is the size of screen on the iPhone perfect also by any chance?

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I use my iPad when laying in bed or on the couch, I think a lot of people have them for this reason. Therefore portability is not a concern for me. In fact this would be a reason to own two of them, one for portability (current size), and one for better viewing pleasure at home.
But not everyone needs their tablet to be portable.
I have owned my iPad since the very 1st launch day and it's been out the house twice.
Weight is also a non issue, I don't stand up holding the iPad is free air, It's either on the bed, on a table or on my lap.
Whilst I admit, light and thin are to nice things, it could be twice and thick and twice as heavy, and, to be honest, it would not be THAT much of a deal.
Twice not a lot, is still not a lot.