If it was that easy and financially feasible for the market Mazda is in, they would have done it.
Mazda's been playing it safe for the past few years. Especially with the SkyA platforms starting from scratch with the CX-5. They are finally riding solo without company control from Ford nor the financial restrictions. They need to rebuild their brand image on top of the "Zoom-Zoom" philosophy, and they are doing it all on their own. Fortunately, the SkyA platforms have been selling well and Mazda is finally reporting profit. Hopefully that allows them to have the finance for R&D on more interesting vehicles like they once had in the 1980's and early 1990's before the collapse. Yes, they had cars and designs that competed with the big boys from Germany.
Mazda's still somewhat hold the positive niche image they've always had. The brand that embodies the "Soul of a sportscar" in every car they produce. The "Zoom-Zoom" brand. They can always build appliances like Toyota and Honda, but they chose not to. Mazda is a relatively small company, and they intend on keeping it that way. All while remaining exciting and profitable.