Ideal or not there is little downside to corvettes. Big ships have more health but it takes a load of health to compete with 75% evasion. Big guns have more damage but that damage struggles to hit evasive targets. Also the speed sounds trivial but it can mean the difference between your fleet fighting alongside your starbase or fighting against your captured starbase.
If you started with cruisers it might be a different story, but there just seems to be better uses of scarce engineering beakers until you are ready to go for battleships. Its less of a choice between
M-sized weapons w/ tracking bonuses hit corvettes well enough and from longer range. Cruisers w/ these counter everything, have overall better stats, and have good speed w/ 2 afterburners. They are also way more survivable, past a certain point its impossible to win even a one-sided battle without a dozen corvettes dying while a bunch of cruisers or battleships in the same situation sustain very few losses if any.