My reaction - Giantism is not that much of a temptation for actual engineers and designers. It is a huge temptation for the Sales Dept., PR Dept., management egos, customer egos, and kids. Admittedly, some folks with "Engineer" or "Designer" in their job titles are, mentally, more in those other places.
Somewhat related, but not actually giantism, is feature bloat. Instead of the biggest just-plain-knife in the world, you have the Swiss Army Knife with the most different blades & tools & accessories & crap. That's more often a temptation for engineers & designers.
A different beast, which can be mistaken for giantism, is economics-driven limit-pushing. Doesn't matter if it's large overall size (wind turbines), small feature size (IC's), high efficiency (commercial jet engines), high pressure (rocket engine combustion chambers), or what. The company which can reliably out-do its rivals in the metric is well-positioned to crush them, via better economic performance. (Perhaps making the company a financial giant...)