Language is always changing. The object 것 (thing) and subject particle 이 (marking the subject of the clause) as you state, are being contracted. But the standard language (표준 언어) is 것이. While 게 (when used as the contracted form of 것이 is not standard language but a form of the standard adopted by generations that "made it their own".

I am also familiar with the ㅅ being dropped. As an example:

그건?? 아니야 그건 안돼! (That (near you)?? No way, that (near you) won't do!)

edit

Also consider that these two "match" well with the level of respect to the hearer in their conjugations:

그게 좋아
그것이 좋습니다

as for the "middle" level, it could go either way

그게 좋아요

 

그것이 좋아요

Language is always changing. The object 것 (thing) and subject particle 이 (marking the subject of the clause) as you state, are being contracted. But the standard language (표준 언어) is 것이. While 게 (when used as the contracted form of 것이 is not standard language but a form of the standard adopted by generations that "made it their own".

I am also familiar with the ㅅ being dropped. As an example:

그건?? 아니야 그건 안돼! (That (near you)?? No way, that (near you) won't do!)

edit

Also consider that these two "match" well with the level of respect to the hearer in their conjugations:

그게 좋아
그것이 좋습니다

as for the "middle" level, it could go either way

그게 좋아요

그것이 좋아요

Language is always changing. The object 것 (thing) and subject particle 이 (marking the subject of the clause) as you state, are being contracted. But the standard language (표준 언어) is 것이. While 게 (when used as the contracted form of 것이 is not standard language but a form of the standard adopted by generations that "made it their own".

I am also familiar with the ㅅ being dropped. As an example:

그건?? 아니야 그건 안돼! (That (near you)?? No way, that (near you) won't do!)

Language is always changing. The object 것 (thing) and subject particle 이 (marking the subject of the clause) as you state, are being contracted. But the standard language (표준 언어) is 것이. While 게 (when used as the contracted form of 것이 is not standard language but a form of the standard adopted by generations that "made it their own".

I am also familiar with the ㅅ being dropped. As an example:

그건?? 아니야 그건 안돼! (That (near you)?? No way, that (near you) won't do!)

edit

Also consider that these two "match" well with the level of respect to the hearer in their conjugations:

그게 좋아
그것이 좋습니다

as for the "middle" level, it could go either way

그게 좋아요

그것이 좋아요