Having a mechanical engineer drive the design of a battery pack isn't necessarily a bad thing, IMO it's the sensible route for a mass-market car made by a mass-market company.
Modern high volume, quality focused manufacturing will often prioritize ease of assembly over elegance in design. Fewer, simpler steps make for fewer defects and greater product consistency. It's the whole "lean manufacturing" ideal at play, done right it will lower costs and improve quality to a point that you can splurge on a little engineering elegance such as a small-volume hybrid model capable of being assembled on the same line as your high-volume offerings. Tesla doesn't have to worry about this for now as they compete in a high-margin segment of the industry and they are trying to set a benchmark of excellence that will create demand for their products.
A real world example I've seen in person is the Nissan Leaf. The battery is designed to be as safe as possible for handling by a line worker and that allows Nissan to produce the Leaf at the exact same time as plain vanilla Altimas are rolling down the line. If you ever take a tour of their Smyrna, TN plant you'll see 1 line with a 9 or 10 Altimas interspersed with a Leaf every once in a while. It's smart engineering at a production-level viewpoint as a "worse" battery allows an entirely different product to be produced with minimal production overhead.
Modern high volume, quality focused manufacturing will often prioritize ease of assembly over elegance in design. Fewer, simpler steps make for fewer defects and greater product consistency. It's the whole "lean manufacturing" ideal at play, done right it will lower costs and improve quality to a point that you can splurge on a little engineering elegance such as a small-volume hybrid model capable of being assembled on the same line as your high-volume offerings. Tesla doesn't have to worry about this for now as they compete in a high-margin segment of the industry and they are trying to set a benchmark of excellence that will create demand for their products.
A real world example I've seen in person is the Nissan Leaf. The battery is designed to be as safe as possible for handling by a line worker and that allows Nissan to produce the Leaf at the exact same time as plain vanilla Altimas are rolling down the line. If you ever take a tour of their Smyrna, TN plant you'll see 1 line with a 9 or 10 Altimas interspersed with a Leaf every once in a while. It's smart engineering at a production-level viewpoint as a "worse" battery allows an entirely different product to be produced with minimal production overhead.