In many ways the fate of Graf Zeppelin mirrors the state of the Kriegsmarine itself , a service which was developed in the shadow of the Luftwaffe and the Wehrmacht and which was something of a Cinderella in terms of the pecking order for resources. the "big ship" thinkers thinking in terms of the "big gun" rather than the carrier.
The shifting priorites are understandable given the mess the Kriegsmarine found itself in when war broke out - a handful of submarines and a poorly balanced surface fleet which was greatly outnumbered , little wonder that Raeder said that all he could expect was that they would die with honour.
The design does look similar to the
Akagi and was heavily influenced by an inspection of that ship , although initially design insights were initially borrowed from the British
Courageous and the American
LexingtonFor the Germans this was virgin territory - they had no experience of carrier design and it was catch up all the way and it is not unreasonable to think that the same problems which existed in the design of the heavy cruisers would have existed in Graf Zeppelin in terms of mechanical vunerability within the steam turbines.
The Graf Zeppelin is a story of might have beens and perhaps should have beens , had she been ready for sea in 1941 and been with
Bismarck (instead of
Prinz Eugen) would things have been different ?
The navy was in an impossible position in 1939 and the directions which the war took further compromised them - decisions taken were often over taken by the changing political and military situations and priorities demanded yet another change in direction.
With hindsight a ship which was needed earlier which could have been in service later , by which time the opportunity for a productive deployment had passed.

( From Whitely's "
German Capital Sips of World War two". This book provides a detailed yet concise history of the development and lack of directional thinking in how in the event of the ship(s) could or would be used.
It seems that the war left the servcie having to be always reactive in terms of planning.