Is the marketing designed to encourage people to purchase more processing power than they may need because of unknowns?
probably not - it is just a envelopment in progress. Over time the processing power gets better and better and even my 2005 Mac PRO Quad Core G5 was sufficient for all I had done in that time - and i guess i'd still be quite happy with it even now.
That said you can't have too much horsepower on a LapTop. The less you need the longer your battery lasts.
Many people claim the MBAs have a very long battery life - well - if you start editing images e.g. in LightRoom the battery life goes down dramatically - if you then edit the very same images in a rMBP 13 the number of edited images is significantly higher before the battery is flat since the MBA is throttling the processor much earlier due to heat dissipation reasons.
RAW files should be no problem with all the models you can buy - it is IMHO more a question of size and weight you're willing to accept. For me 13 inch is the sweet spot and I always get the maxed out configuration because you can't upgrade later on. I use my MACs normally > 5 years. In that time frame the features and possibilities change a lot.
My previous maxed out MBA 2010 had 4 GB Ram and 256 GB SSD and a Geekbench Result of 3100 - my current rMBP 13 has 16 GB RAM and 1 TB SSD and a Geekbench Result of 7200 - four years later - but most of all - it can do 4k video output, it has 2x TB2 and USB 3.0 and HDMI and the SSD is 4x faster and the battery life in real world applications is ⅓ longer!!
Within the current product line the performance difference is not so big between the smalls and the biggest possible configuration - yet the possible resale price differs dramatically.
There are dozens of professional resellers of used MACs - including ebay - the top configurations sell best - no wonder - but the even overcompensate for the extra payed investment at the beginning.
I sold my 2009 Mac Pro 8x 2,67 GHz for 38 % of the purchasing price after five years of using the machine. The smaller configurations would have brought maybe 25 to 30 % of the former purchasing price at a german reseller of used MACs
Additionally you have normally in the top configuration as much horse power as the entry configuration four years later - thus the time of using the machine goes up.
If you are use to shorter time frames gor for a lower configuration - if you're like me keeping your computers >4-5 years gor for a good equipped one - keep in mind: you can never have too much RAM - MACs consume easily 16 GB and you will notice the speed difference even with a very fast SSD - especially with PS and big files.
Fir me the maxed out rMBP 13 is the perfect combination of portability plus enough horsepower and with 2x TB2 and 4k support it is absolutely future-proof fr the coming years.
Go to an Apple store - the guys will address all your questions and help you judging what you really need - but from my perspective the maxed out configuration is the one that suits normally best for a long usage period - 4 GB of RAM in my old MBA was just too low - even though it was the maximum configuration that time - and it can't be upgraded!!
