BGA saves money and in my opinion, part of a broader initiative (eg. chipset integration) to reduce the total cost (BOM, logistics, channels) of other components so there can be more left for Intel/processor. This is nothing new: twas the initial thrust behind integrated graphics back in the late 90's.
While Upgradeability has been a key feature of PCs and more or less a sacred cow, its also the biggest and perhaps the only remaining area where significant cost can be taken out of the PC eco-system.
Moreover, if you believe the vast majority of PC customers today value small form factor/integration/power savings >>> upgradeability, then its a win win.
Make no mistake: Intel's profitability level and cash flow (already: market has to be a little shocked that they raised $6B debt this week - I would be) is in jeopardy because of higher capex and resultant depreciation and something has to be done about protecting and perhaps raising ASP and this is not only the low lying fruit, its also nothing new for Intel.
Personally, I like it. There's a lot of unnecessary BOM, logistics and channel costs in PCs today, this will deliver more value to customers and make PCs more competitive with the Apple/Chrome/ARM tidal wave - intel needs this badly esp. given Microsoft's lacklustre operating system...talk about a perfect storm.